hive支持sql大全（收藏版）

傷城~ 2022-09-26 00:28 79阅读 0赞

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           <div style="margin-left:10px; width:auto"></div> <em>本帖最后由 pig2 于 2014-4-13 16:20 编辑 </em><br> hive操作数据库还是比较方便的，因此才会有hbase与hive整合。下面我们hive的强大功能吧。为了增强阅读性，下面提几个问题：<br> <strong><span style="color:#ff0000">hive支持哪些运算符？</span><br> <span style="color:#ff0000">hive是否支持左右连接？</span><br> <span style="color:#ff0000">hive如何截取字符串？</span><br> <span style="color:#ff0000">hive提供了那些系统函数？</span></strong><br> <br> <br> 
           <div> 
            <span style="font-family:宋体">目录</span> 
           </div> 
           <div>
             一、关系运算：... 4 
           </div> 
           <div>
             1. 等值比较: =. 4 
           </div> 
           <div>
             2. 不等值比较: &lt;&gt;. 4 
           </div> 
           <div>
             3. 小于比较: &lt;. 4 
           </div> 
           <div>
             4. 小于等于比较: &lt;=. 4 
           </div> 
           <div>
             5. 大于比较: &gt;. 5 
           </div> 
           <div>
             6. 大于等于比较: &gt;=. 5 
           </div> 
           <div>
             7. 空值判断: IS NULL. 5 
           </div> 
           <div>
             8. 非空判断: IS NOT NULL. 6 
           </div> 
           <div>
             9. LIKE比较: LIKE. 6 
           </div> 
           <div>
             10. JAVA的LIKE操作: RLIKE. 6 
           </div> 
           <div>
             11. REGEXP操作: REGEXP. 7 
           </div> 
           <div>
             二、数学运算：... 7 
           </div> 
           <div>
             1. 加法操作: +. 7 
           </div> 
           <div>
             2. 减法操作: - 7 
           </div> 
           <div>
             3. 乘法操作: *. 8 
           </div> 
           <div>
             4. 除法操作: /. 8 
           </div> 
           <div>
             5. 取余操作: %.. 8 
           </div> 
           <div>
             6. 位与操作: &amp;.. 9 
           </div> 
           <div>
             7. 位或操作: |. 9 
           </div> 
           <div>
             8. 位异或操作: ^. 9 
           </div> 
           <div>
             9．位取反操作: ~. 10 
           </div> 
           <div>
             三、逻辑运算：... 10 
           </div> 
           <div>
             1. 逻辑与操作: AND.. 10 
           </div> 
           <div>
             2. 逻辑或操作: OR. 10 
           </div> 
           <div>
             3. 逻辑非操作: NOT. 10 
           </div> 
           <div>
             四、数值计算... 11 
           </div> 
           <div>
             1. 取整函数: round. 11 
           </div> 
           <div>
             2. 指定精度取整函数: round. 11 
           </div> 
           <div>
             3. 向下取整函数: floor. 11 
           </div> 
           <div>
             4. 向上取整函数: ceil 12 
           </div> 
           <div>
             5. 向上取整函数: ceiling. 12 
           </div> 
           <div>
             6. 取随机数函数: rand. 12 
           </div> 
           <div>
             7. 自然指数函数: exp. 13 
           </div> 
           <div>
             8. 以10为底对数函数: log10. 13 
           </div> 
           <div>
             9. 以2为底对数函数: log2. 13 
           </div> 
           <div>
             10. 对数函数: log. 13 
           </div> 
           <div>
             11. 幂运算函数: pow.. 14 
           </div> 
           <div>
             12. 幂运算函数: power. 14 
           </div> 
           <div>
             13. 开平方函数: sqrt. 14 
           </div> 
           <div>
             14. 二进制函数: bin. 14 
           </div> 
           <div>
             15. 十六进制函数: hex. 15 
           </div> 
           <div>
             16. 反转十六进制函数: unhex. 15 
           </div> 
           <div>
             17. 进制转换函数: conv. 15 
           </div> 
           <div>
             18. 绝对值函数: abs. 16 
           </div> 
           <div>
             19. 正取余函数: pmod. 16 
           </div> 
           <div>
             20. 正弦函数: sin. 16 
           </div> 
           <div>
             21. 反正弦函数: asin. 16 
           </div> 
           <div>
             22. 余弦函数: cos. 17 
           </div> 
           <div>
             23. 反余弦函数: acos. 17 
           </div> 
           <div>
             24. positive函数: positive. 17 
           </div> 
           <div>
             25. negative函数: negative. 17 
           </div> 
           <div>
             五、日期函数... 18 
           </div> 
           <div>
             1. UNIX时间戳转日期函数: from_unixtime. 18 
           </div> 
           <div>
             2. 获取当前UNIX时间戳函数: unix_timestamp. 18 
           </div> 
           <div>
             3. 日期转UNIX时间戳函数: unix_timestamp. 18 
           </div> 
           <div>
             4. 指定格式日期转UNIX时间戳函数: unix_timestamp. 18 
           </div> 
           <div>
             5. 日期时间转日期函数: to_date. 19 
           </div> 
           <div>
             6. 日期转年函数: year. 19 
           </div> 
           <div>
             7. 日期转月函数: month. 19 
           </div> 
           <div>
             8. 日期转天函数: day. 19 
           </div> 
           <div>
             9. 日期转小时函数: hour. 20 
           </div> 
           <div>
             10. 日期转分钟函数: minute. 20 
           </div> 
           <div>
             11. 日期转秒函数: second. 20 
           </div> 
           <div>
             12. 日期转周函数: weekofyear. 20 
           </div> 
           <div>
             13. 日期比较函数: datediff 21 
           </div> 
           <div>
             14. 日期增加函数: date_add. 21 
           </div> 
           <div>
             15. 日期减少函数: date_sub. 21 
           </div> 
           <div>
             六、条件函数... 21 
           </div> 
           <div>
             1. If函数: if 21 
           </div> 
           <div>
             2. 非空查找函数: COALESCE. 22 
           </div> 
           <div>
             3. 条件判断函数：CASE. 22 
           </div> 
           <div>
             4. 条件判断函数：CASE. 22 
           </div> 
           <div>
             七、字符串函数... 23 
           </div> 
           <div>
             1. 字符串长度函数：length. 23 
           </div> 
           <div>
             2. 字符串反转函数：reverse. 23 
           </div> 
           <div>
             3. 字符串连接函数：concat. 23 
           </div> 
           <div>
             4. 带分隔符字符串连接函数：concat_ws. 23 
           </div> 
           <div>
             5. 字符串截取函数：substr,substring. 24 
           </div> 
           <div>
             6. 字符串截取函数：substr,substring. 24 
           </div> 
           <div>
             7. 字符串转大写函数：upper,ucase. 24 
           </div> 
           <div>
             8. 字符串转小写函数：lower,lcase. 25 
           </div> 
           <div>
             9. 去空格函数：trim.. 25 
           </div> 
           <div>
             10. 左边去空格函数：ltrim.. 25 
           </div> 
           <div>
             11. 右边去空格函数：rtrim.. 25 
           </div> 
           <div>
             12. 正则表达式替换函数：regexp_replace. 26 
           </div> 
           <div>
             13. 正则表达式解析函数：regexp_extract. 26 
           </div> 
           <div>
             14. URL解析函数：parse_url 26 
           </div> 
           <div>
             15. json解析函数：get_json_object. 27 
           </div> 
           <div>
             16. 空格字符串函数：space. 27 
           </div> 
           <div>
             17. 重复字符串函数：repeat. 27 
           </div> 
           <div>
             18. 首字符ascii函数：ascii 28 
           </div> 
           <div>
             19. 左补足函数：lpad. 28 
           </div> 
           <div>
             20. 右补足函数：rpad. 28 
           </div> 
           <div>
             21. 分割字符串函数: split. 28 
           </div> 
           <div>
             22. 集合查找函数: find_in_set. 29 
           </div> 
           <div>
             八、集合统计函数... 29 
           </div> 
           <div>
             1. 个数统计函数: count. 29 
           </div> 
           <div>
             2. 总和统计函数: sum.. 29 
           </div> 
           <div>
             3. 平均值统计函数: avg. 30 
           </div> 
           <div>
             4. 最小值统计函数: min. 30 
           </div> 
           <div>
             5. 最大值统计函数: max. 30 
           </div> 
           <div>
             6. 非空集合总体变量函数: var_pop. 30 
           </div> 
           <div>
             7. 非空集合样本变量函数: var_samp. 31 
           </div> 
           <div>
             8. 总体标准偏离函数: stddev_pop. 31 
           </div> 
           <div>
             9. 样本标准偏离函数: stddev_samp. 31 
           </div> 
           <div>
             10．中位数函数: percentile. 31 
           </div> 
           <div>
             11. 中位数函数: percentile. 31 
           </div> 
           <div>
             12. 近似中位数函数: percentile_approx. 32 
           </div> 
           <div>
             13. 近似中位数函数: percentile_approx. 32 
           </div> 
           <div>
             14. 直方图: histogram_numeric. 32 
           </div> 
           <div>
             九、复合类型构建操作... 32 
           </div> 
           <div>
             1. Map类型构建: map. 32 
           </div> 
           <div>
             2. Struct类型构建: struct. 33 
           </div> 
           <div>
             3. array类型构建: array. 33 
           </div> 
           <div>
             十、复杂类型访问操作... 33 
           </div> 
           <div>
             1. array类型访问: A[n] 33 
           </div> 
           <div>
             2. map类型访问: M[key] 34 
           </div> 
           <div>
             3. struct类型访问: S.x. 34 
           </div> 
           <div>
             十一、复杂类型长度统计函数... 34 
           </div> 
           <div>
             1.&nbsp; &nbsp;&nbsp; &nbsp;Map类型长度函数: size(Map&lt;K.V&gt;) 34 
           </div> 
           <div>
             2.&nbsp; &nbsp;&nbsp; &nbsp;array类型长度函数: size(Array&lt;T&gt;) 34 
           </div> 
           <div>
             3.&nbsp; &nbsp;&nbsp; &nbsp;类型转换函数... 35 
           </div> <br> 
           <div> 
            <br> 
            <img src="http://www.aboutyun.com/static/image/hrline/2.gif" alt="" width="485" height="21" style=""> 
            <br> 
            <br> 
            <br> 
           </div> <br> <br> <br> <br> <strong><span style="font-family:宋体">一、关系运算：</span>1. <span style="font-family:宋体"> 等值比较</span>: =</strong> 
           <div>
             &nbsp; &nbsp;&nbsp; &nbsp;&nbsp; &nbsp; 
            <span style="font-family:宋体">语法：</span>A=B 
           </div> 
           <div>
             &nbsp; &nbsp;&nbsp; &nbsp;&nbsp; &nbsp; 
            <span style="font-family:宋体">操作类型：所有基本类型</span> 
           </div> 
           <div>
             &nbsp; &nbsp;&nbsp; &nbsp;&nbsp; &nbsp; 
            <span style="font-family:宋体">描述</span>: 
            <span style="font-family:宋体"> 如果表达式</span>A 
            <span style="font-family:宋体">与表达式</span>B 
            <span style="font-family:宋体">相等，则为</span>TRUE 
            <span style="font-family:宋体">；否则为</span>FALSE 
           </div> 
           <div>
             &nbsp; &nbsp;&nbsp; &nbsp;&nbsp; &nbsp; 
            <span style="font-family:宋体">举例：</span> 
           </div> 
           <div>
             &nbsp; &nbsp;&nbsp; &nbsp;&nbsp; &nbsp;hive&gt;select 1 from lxw_dual where 1=1; 
           </div> 
           <div>
             &nbsp; &nbsp;&nbsp; &nbsp;&nbsp; &nbsp;1 
           </div> <strong>2. <span style="font-family:宋体">不等值比较</span>: &lt;&gt;</strong> 
           <div>
             &nbsp; &nbsp;&nbsp; &nbsp;&nbsp; &nbsp; 
            <span style="font-family:宋体">语法</span>: A &lt;&gt; B 
           </div> 
           <div>
             操作类型: 所有基本类型 
           </div> 
           <div>
             描述: 如果表达式A为NULL，或者表达式B为NULL，返回NULL；如果表达式A与表达式B不相等，则为TRUE；否则为FALSE 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select1 from lxw_dual where 1 &lt;&gt; 2; 
           </div> 
           <div>
             1 
           </div> <strong><span style="font-size:9.5pt">3. </span><span style="font-family:宋体">小于比较</span>: &lt;</strong> 
           <div>
             &nbsp; &nbsp;&nbsp; &nbsp;&nbsp; &nbsp; 
            <span style="font-family:宋体">语法</span>: A &lt; B 
           </div> 
           <div>
             操作类型: 所有基本类型 
           </div> 
           <div>
             描述: 如果表达式A为NULL，或者表达式B为NULL，返回NULL；如果表达式A小于表达式B，则为TRUE；否则为FALSE 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select1 from lxw_dual where 1 &lt; 2; 
           </div> 
           <div>
             1 
           </div> <br> <strong>4. <span style="font-family:宋体">小于等于比较</span>: &lt;=</strong> 
           <div>
             语法: A &lt;= B 
           </div> 
           <div>
             操作类型: 所有基本类型 
           </div> 
           <div>
             描述: 如果表达式A为NULL，或者表达式B为NULL，返回NULL；如果表达式A小于或者等于表达式B，则为TRUE；否则为FALSE 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select1 from lxw_dual where 1 &lt;= 1; 
           </div> 
           <div>
             1 
           </div> <strong>5. <span style="font-family:宋体">大于比较</span>: &gt;</strong> 
           <div>
             语法: A &gt; B 
           </div> 
           <div>
             操作类型: 所有基本类型 
           </div> 
           <div>
             描述: 如果表达式A为NULL，或者表达式B为NULL，返回NULL；如果表达式A大于表达式B，则为TRUE；否则为FALSE 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select1 from lxw_dual where 2 &gt; 1; 
           </div> 
           <div>
             1 
           </div> <br> <strong>6. <span style="font-family:宋体">大于等于比较</span>: &gt;=</strong> 
           <div>
             语法: A &gt;= B 
           </div> 
           <div>
             操作类型: 所有基本类型 
           </div> 
           <div>
             描述: 如果表达式A为NULL，或者表达式B为NULL，返回NULL；如果表达式A大于或者等于表达式B，则为TRUE；否则为FALSE 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select1 from lxw_dual where 1 &gt;= 1; 
           </div> 
           <div>
             1 
           </div> <br> 
           <div> 
            <strong>注意：String的比较要注意(常用的时间比较可以先to_date之后再比较)</strong> 
           </div> 
           <div>
             hive&gt; select* from lxw_dual; 
           </div> 
           <div>
             OK 
           </div> 
           <div>
             201111120900:00:00&nbsp; &nbsp;&nbsp;&nbsp;2011111209 
           </div> <br> 
           <div>
             hive&gt; selecta,b,a&lt;b,a&gt;b,a=b from lxw_dual; 
           </div> 
           <div>
             201111120900:00:00&nbsp; &nbsp;&nbsp;&nbsp;2011111209&nbsp; &nbsp;&nbsp; &nbsp;false&nbsp;&nbsp;true&nbsp; &nbsp; false 
           </div> <br> <strong>7. <span style="font-family:宋体">空值判断</span>: IS NULL</strong> 
           <div>
             语法: A IS NULL 
           </div> 
           <div>
             操作类型: 所有类型 
           </div> 
           <div>
             描述: 如果表达式A的值为NULL，则为TRUE；否则为FALSE 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select1 from lxw_dual where null is null; 
           </div> 
           <div>
             1 
           </div> <br> <strong>8. <span style="font-family:宋体">非空判断</span>: IS NOTNULL</strong> 
           <div>
             语法: A IS NOT NULL 
           </div> 
           <div>
             操作类型: 所有类型 
           </div> 
           <div>
             描述: 如果表达式A的值为NULL，则为FALSE；否则为TRUE 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select1 from lxw_dual where 1 is not null; 
           </div> 
           <div>
             1 
           </div> <br> <strong>9. LIKE<span style="font-family:宋体">比较</span>: LIKE</strong> 
           <div>
             语法: A LIKE B 
           </div> 
           <div>
             操作类型: strings 
           </div> 
           <div>
             描述: 如果字符串A或者字符串B为NULL，则返回NULL；如果字符串A符合表达式B&nbsp; &nbsp;的正则语法，则为TRUE；否则为FALSE。B中字符”_”表示任意单个字符，而字符”%”表示任意数量的字符。 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select1 from lxw_dual where 'football' like 'foot%'; 
           </div> 
           <div>
             1 
           </div> 
           <div>
             hive&gt; select1 from lxw_dual where 'football' like 'foot____'; 
           </div> 
           <div>
             1 
           </div> 
           <div> 
            <strong>注意：否定比较时候用NOT ALIKE B</strong> 
           </div> 
           <div>
             hive&gt; select1 from lxw_dual where NOT 'football' like 'fff%'; 
           </div> 
           <div>
             1 
           </div> <br> <strong>10. JAVA<span style="font-family:宋体">的</span>LIKE<span style="font-family:宋体">操作</span>: RLIKE</strong> 
           <div>
             语法: A RLIKE B 
           </div> 
           <div>
             操作类型: strings 
           </div> 
           <div>
             描述: 如果字符串A或者字符串B为NULL，则返回NULL；如果字符串A符合JAVA正则表达式B的正则语法，则为TRUE；否则为FALSE。 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select1 from lxw_dual where 'footbar’ rlike '^f.*r$’; 
           </div> 
           <div>
             1 
           </div> 
           <div> 
            <strong>注意：判断一个字符串是否全为数字：</strong> 
           </div> 
           <div>
             hive&gt;select 1from lxw_dual where '123456' rlike '^\\d+$'; 
           </div> 
           <div>
             1 
           </div> 
           <div>
             hive&gt; select1 from lxw_dual where '123456aa' rlike '^\\d+$'; 
           </div> <br> <strong>11. REGEXP<span style="font-family:宋体">操作</span>: REGEXP</strong> 
           <div>
             语法: A REGEXP B 
           </div> 
           <div>
             操作类型: strings 
           </div> 
           <div>
             描述: 功能与RLIKE相同 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select1 from lxw_dual where 'footbar' REGEXP '^f.*r$'; 
           </div> 
           <div>
             1 
           </div> <strong><span style="font-family:宋体">二、数学运算：</span>1. <span style="font-family:宋体"> 加法操作</span>: +</strong> 
           <div>
             语法: A + B 
           </div> 
           <div>
             操作类型：所有数值类型 
           </div> 
           <div>
             说明：返回A与B相加的结果。结果的数值类型等于A的类型和B的类型的最小父类型（详见数据类型的继承关系）。比如，int + int 一般结果为int类型，而int + double 一般结果为double类型 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select1 + 9 from lxw_dual; 
           </div> 
           <div>
             10 
           </div> 
           <div>
             hive&gt; createtable lxw_dual as select 1 + 1.2 from lxw_dual; 
           </div> 
           <div>
             hive&gt;describe lxw_dual; 
           </div> 
           <div>
             _c0&nbsp; &nbsp;&nbsp;&nbsp;double 
           </div> <br> <strong>2. <span style="font-family:宋体">减法操作</span>: -</strong> 
           <div>
             语法: A – B 
           </div> 
           <div>
             操作类型：所有数值类型 
           </div> 
           <div>
             说明：返回A与B相减的结果。结果的数值类型等于A的类型和B的类型的最小父类型（详见数据类型的继承关系）。比如，int – int 一般结果为int类型，而int – double 一般结果为double类型 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select10 – 5 from lxw_dual; 
           </div> 
           <div>
             5 
           </div> 
           <div>
             hive&gt; createtable lxw_dual as select 5.6 – 4 from lxw_dual; 
           </div> 
           <div>
             hive&gt;describe lxw_dual; 
           </div> 
           <div>
             _c0&nbsp; &nbsp;&nbsp;&nbsp;double 
           </div> <br> <strong>3. <span style="font-family:宋体">乘法操作</span>: *</strong> 
           <div>
             语法: A * B 
           </div> 
           <div>
             操作类型：所有数值类型 
           </div> 
           <div>
             说明：返回A与B相乘的结果。结果的数值类型等于A的类型和B的类型的最小父类型（详见数据类型的继承关系）。注意，如果A乘以B的结果超过默认结果类型的数值范围，则需要通过cast将结果转换成范围更大的数值类型 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select40 * 5 from lxw_dual; 
           </div> 
           <div>
             200 
           </div> <br> <strong>4. <span style="font-family:宋体">除法操作</span>: /</strong> 
           <div>
             语法: A / B 
           </div> 
           <div>
             操作类型：所有数值类型 
           </div> 
           <div>
             说明：返回A除以B的结果。结果的数值类型为double 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select40 / 5 from lxw_dual; 
           </div> 
           <div>
             8.0 
           </div> <br> 
           <div> 
            <strong>注意：hive中最高精度的数据类型是double,只精确到小数点后16位，在做除法运算的时候要特别注意</strong> 
           </div> 
           <div>
             hive&gt;select ceil(28.0/6.999999999999999999999) from lxw_duallimit 1;&nbsp; &nbsp; 
           </div> 
           <div>
             结果为4 
           </div> 
           <div>
             hive&gt;select ceil(28.0/6.99999999999999) from lxw_dual limit1;&nbsp; &nbsp;&nbsp; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; 
           </div> 
           <div>
             结果为5 
           </div> <br> <strong>5. <span style="font-family:宋体">取余操作</span>: %</strong> 
           <div>
             语法: A % B 
           </div> 
           <div>
             操作类型：所有数值类型 
           </div> 
           <div>
             说明：返回A除以B的余数。结果的数值类型等于A的类型和B的类型的最小父类型（详见数据类型的继承关系）。 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select 41 % 5 from lxw_dual; 
           </div> 
           <div>
             1 
           </div> 
           <div>
             hive&gt; select 8.4 % 4 from lxw_dual; 
           </div> 
           <div>
             0.40000000000000036 
           </div> 
           <div> 
            <strong>注意：精度在hive中是个很大的问题，类似这样的操作最好通过round指定精度</strong> 
           </div> 
           <div>
             hive&gt; select round(8.4 % 4 , 2) from lxw_dual; 
           </div> 
           <div>
             0.4 
           </div> <strong>6. <span style="font-family:宋体">位与操作</span>: &amp;</strong> 
           <div>
             语法: A &amp; B 
           </div> 
           <div>
             操作类型：所有数值类型 
           </div> 
           <div>
             说明：返回A和B按位进行与操作的结果。结果的数值类型等于A的类型和B的类型的最小父类型（详见数据类型的继承关系）。 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select 4 &amp; 8 from lxw_dual; 
           </div> 
           <div>
             0 
           </div> 
           <div>
             hive&gt; select 6 &amp; 4 from lxw_dual; 
           </div> 
           <div>
             4 
           </div> <br> <strong>7. <span style="font-family:宋体">位或操作</span>: |</strong> 
           <div>
             语法: A | B 
           </div> 
           <div>
             操作类型：所有数值类型 
           </div> 
           <div>
             说明：返回A和B按位进行或操作的结果。结果的数值类型等于A的类型和B的类型的最小父类型（详见数据类型的继承关系）。 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select 4 | 8 from lxw_dual; 
           </div> 
           <div>
             12 
           </div> 
           <div>
             hive&gt; select 6 | 8 from lxw_dual; 
           </div> 
           <div>
             14 
           </div> <br> <strong>8. <span style="font-family:宋体">位异或操作</span>: ^</strong> 
           <div>
             语法: A ^ B 
           </div> 
           <div>
             操作类型：所有数值类型 
           </div> 
           <div>
             说明：返回A和B按位进行异或操作的结果。结果的数值类型等于A的类型和B的类型的最小父类型（详见数据类型的继承关系）。 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select 4 ^ 8 from lxw_dual; 
           </div> 
           <div>
             12 
           </div> 
           <div>
             hive&gt; select 6 ^ 4 from lxw_dual; 
           </div> 
           <div>
             2 
           </div> <br> <strong>9<span style="font-family:宋体">．位取反操作</span>: ~</strong> 
           <div>
             语法: ~A 
           </div> 
           <div>
             操作类型：所有数值类型 
           </div> 
           <div>
             说明：返回A按位取反操作的结果。结果的数值类型等于A的类型。 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select ~6 from lxw_dual; 
           </div> 
           <div>
             -7 
           </div> 
           <div>
             hive&gt; select ~4 from lxw_dual; 
           </div> 
           <div>
             -5 
           </div> <strong><span style="font-family:宋体">三、逻辑运算：</span>1. <span style="font-family:宋体"> 逻辑与操作</span>: AND</strong> 
           <div>
             语法: A AND B 
           </div> 
           <div>
             操作类型：boolean 
           </div> 
           <div>
             说明：如果A和B均为TRUE，则为TRUE；否则为FALSE。如果A为NULL或B为NULL，则为NULL 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select 1 from lxw_dual where 1=1 and 2=2; 
           </div> 
           <div>
             1 
           </div> <br> <strong>2. <span style="font-family:宋体">逻辑或操作</span>: OR</strong> 
           <div>
             语法: A OR B 
           </div> 
           <div>
             操作类型：boolean 
           </div> 
           <div>
             说明：如果A为TRUE，或者B为TRUE，或者A和B均为TRUE，则为TRUE；否则为FALSE 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select 1 from lxw_dual where 1=2 or 2=2; 
           </div> 
           <div>
             1 
           </div> <br> <strong>3. <span style="font-family:宋体">逻辑非操作</span>: NOT</strong> 
           <div>
             语法: NOT A 
           </div> 
           <div>
             操作类型：boolean 
           </div> 
           <div>
             说明：如果A为FALSE，或者A为NULL，则为TRUE；否则为FALSE 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select 1 from lxw_dual where not 1=2; 
           </div> 
           <div>
             1 
           </div> <br> <strong><span style="font-family:宋体">四、数值计算</span>1. <span style="font-family:宋体"> 取整函数</span>: round</strong> 
           <div>
             语法: round(double a) 
           </div> 
           <div>
             返回值: BIGINT 
           </div> 
           <div>
             说明: 返回double类型的整数值部分（遵循四舍五入） 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select round(3.1415926) from lxw_dual; 
           </div> 
           <div>
             3 
           </div> 
           <div>
             hive&gt; select round(3.5) from lxw_dual; 
           </div> 
           <div>
             4 
           </div> 
           <div>
             hive&gt; create table lxw_dual as select round(9542.158) fromlxw_dual; 
           </div> 
           <div>
             hive&gt; describe lxw_dual; 
           </div> 
           <div>
             _c0&nbsp; &nbsp;&nbsp;&nbsp;bigint 
           </div> <br> <strong>2. <span style="font-family:宋体">指定精度取整函数</span>: round</strong> 
           <div>
             语法: round(double a, int d) 
           </div> 
           <div>
             返回值: DOUBLE 
           </div> 
           <div>
             说明: 返回指定精度d的double类型 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select round(3.1415926,4) from lxw_dual; 
           </div> 
           <div>
             3.1416 
           </div> <br> <strong>3. <span style="font-family:宋体">向下取整函数</span>: floor</strong> 
           <div>
             语法: floor(double a) 
           </div> 
           <div>
             返回值: BIGINT 
           </div> 
           <div>
             说明: 返回等于或者小于该double变量的最大的整数 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select floor(3.1415926) from lxw_dual; 
           </div> 
           <div>
             3 
           </div> 
           <div>
             hive&gt; select floor(25) from lxw_dual; 
           </div> 
           <div>
             25 
           </div> <br> <strong>4. <span style="font-family:宋体">向上取整函数</span>: ceil</strong> 
           <div>
             语法: ceil(double a) 
           </div> 
           <div>
             返回值: BIGINT 
           </div> 
           <div>
             说明: 返回等于或者大于该double变量的最小的整数 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select ceil(3.1415926) from lxw_dual; 
           </div> 
           <div>
             4 
           </div> 
           <div>
             hive&gt; select ceil(46) from lxw_dual; 
           </div> 
           <div>
             46 
           </div> <br> <strong>5. <span style="font-family:宋体">向上取整函数</span>: ceiling</strong> 
           <div>
             语法: ceiling(double a) 
           </div> 
           <div>
             返回值: BIGINT 
           </div> 
           <div>
             说明: 与ceil功能相同 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select ceiling(3.1415926) from lxw_dual; 
           </div> 
           <div>
             4 
           </div> 
           <div>
             hive&gt; select ceiling(46) from lxw_dual; 
           </div> 
           <div>
             46 
           </div> <strong>6. <span style="font-family:宋体">取随机数函数</span>: rand</strong> 
           <div>
             语法: rand(),rand(int seed) 
           </div> 
           <div>
             返回值: double 
           </div> 
           <div>
             说明: 返回一个0到1范围内的随机数。如果指定种子seed，则会等到一个稳定的随机数序列 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select rand() from lxw_dual; 
           </div> 
           <div>
             0.5577432776034763 
           </div> 
           <div>
             hive&gt; select rand() from lxw_dual; 
           </div> 
           <div>
             0.6638336467363424 
           </div> 
           <div>
             hive&gt; select rand(100) from lxw_dual; 
           </div> 
           <div>
             0.7220096548596434 
           </div> 
           <div>
             hive&gt; select rand(100) from lxw_dual; 
           </div> 
           <div>
             0.7220096548596434 
           </div> <br> <strong>7. <span style="font-family:宋体">自然指数函数</span>: exp</strong> 
           <div>
             语法: exp(double a) 
           </div> 
           <div>
             返回值: double 
           </div> 
           <div>
             说明: 返回自然对数e的a次方 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select exp(2) from lxw_dual; 
           </div> 
           <div>
             7.38905609893065 
           </div> 
           <div>
             自然对数函数: ln 
           </div> 
           <div>
             语法: ln(double a) 
           </div> 
           <div>
             返回值: double 
           </div> 
           <div>
             说明: 返回a的自然对数 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select ln(7.38905609893065) from lxw_dual; 
           </div> 
           <div>
             2.0 
           </div> <br> <strong>8. <span style="font-family:宋体">以</span>10<span style="font-family:宋体">为底对数函数</span>: log10</strong> 
           <div>
             语法: log10(double a) 
           </div> 
           <div>
             返回值: double 
           </div> 
           <div>
             说明: 返回以10为底的a的对数 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select log10(100) from lxw_dual; 
           </div> 
           <div>
             2.0 
           </div> <br> <strong>9. <span style="font-family:宋体">以</span>2<span style="font-family:宋体">为底对数函数</span>: log2</strong> 
           <div>
             语法: log2(double a) 
           </div> 
           <div>
             返回值: double 
           </div> 
           <div>
             说明: 返回以2为底的a的对数 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select log2(8) from lxw_dual; 
           </div> 
           <div>
             3.0 
           </div> <br> <strong>10. <span style="font-family:宋体">对数函数</span>: log</strong> 
           <div>
             语法: log(double base, double a) 
           </div> 
           <div>
             返回值: double 
           </div> 
           <div>
             说明: 返回以base为底的a的对数 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select log(4,256) from lxw_dual; 
           </div> 
           <div>
             4.0 
           </div> <br> <strong>11. <span style="font-family:宋体">幂运算函数</span>: pow</strong> 
           <div>
             语法: pow(double a, double p) 
           </div> 
           <div>
             返回值: double 
           </div> 
           <div>
             说明: 返回a的p次幂 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select pow(2,4) from lxw_dual; 
           </div> 
           <div>
             16.0 
           </div> <br> <strong>12. <span style="font-family:宋体">幂运算函数</span>: power</strong> 
           <div>
             语法: power(double a, double p) 
           </div> 
           <div>
             返回值: double 
           </div> 
           <div>
             说明: 返回a的p次幂,与pow功能相同 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select power(2,4) from lxw_dual; 
           </div> 
           <div>
             16.0 
           </div> <br> <strong>13. <span style="font-family:宋体">开平方函数</span>: sqrt</strong> 
           <div>
             语法: sqrt(double a) 
           </div> 
           <div>
             返回值: double 
           </div> 
           <div>
             说明: 返回a的平方根 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select sqrt(16) from lxw_dual; 
           </div> 
           <div>
             4.0 
           </div> <br> <strong>14. <span style="font-family:宋体">二进制函数</span>: bin</strong> 
           <div>
             语法: bin(BIGINT a) 
           </div> 
           <div>
             返回值: string 
           </div> 
           <div>
             说明: 返回a的二进制代码表示 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select bin(7) from lxw_dual; 
           </div> 
           <div>
             111 
           </div> <br> <strong>15. <span style="font-family:宋体">十六进制函数</span>: hex</strong> 
           <div>
             语法: hex(BIGINT a) 
           </div> 
           <div>
             返回值: string 
           </div> 
           <div>
             说明: 如果变量是int类型，那么返回a的十六进制表示；如果变量是string类型，则返回该字符串的十六进制表示 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select hex(17) from lxw_dual; 
           </div> 
           <div>
             11 
           </div> 
           <div>
             hive&gt; select hex(‘abc’) from lxw_dual; 
           </div> 
           <div>
             616263 
           </div> <br> <strong>16. <span style="font-family:宋体">反转十六进制函数</span>: unhex</strong> 
           <div>
             语法: unhex(string a) 
           </div> 
           <div>
             返回值: string 
           </div> 
           <div>
             说明: 返回该十六进制字符串所代码的字符串 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select unhex(‘616263’)from lxw_dual; 
           </div> 
           <div>
             abc 
           </div> 
           <div>
             hive&gt; select unhex(‘11’)from lxw_dual; 
           </div> 
           <div>
             - 
           </div> 
           <div>
             hive&gt; select unhex(616263) from lxw_dual; 
           </div> 
           <div>
             abc 
           </div> <br> <strong>17. <span style="font-family:宋体">进制转换函数</span>: conv</strong> 
           <div>
             语法: conv(BIGINT num, int from_base, int to_base) 
           </div> 
           <div>
             返回值: string 
           </div> 
           <div>
             说明: 将数值num从from_base进制转化到to_base进制 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select conv(17,10,16) from lxw_dual; 
           </div> 
           <div>
             11 
           </div> 
           <div>
             hive&gt; select conv(17,10,2) from lxw_dual; 
           </div> 
           <div>
             10001 
           </div> <br> <strong>18. <span style="font-family:宋体">绝对值函数</span>: abs</strong> 
           <div>
             语法: abs(double a)&nbsp; &nbsp;abs(int a) 
           </div> 
           <div>
             返回值: double&nbsp; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp;int 
           </div> 
           <div>
             说明: 返回数值a的绝对值 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select abs(-3.9) from lxw_dual; 
           </div> 
           <div>
             3.9 
           </div> 
           <div>
             hive&gt; select abs(10.9) from lxw_dual; 
           </div> 
           <div>
             10.9 
           </div> <br> <strong>19. <span style="font-family:宋体">正取余函数</span>: pmod</strong> 
           <div>
             语法: pmod(int a, int b),pmod(double a, double b) 
           </div> 
           <div>
             返回值: int double 
           </div> 
           <div>
             说明: 返回正的a除以b的余数 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select pmod(9,4) from lxw_dual; 
           </div> 
           <div>
             1 
           </div> 
           <div>
             hive&gt; select pmod(-9,4) from lxw_dual; 
           </div> 
           <div>
             3 
           </div> <br> <strong>20. <span style="font-family:宋体">正弦函数</span>: sin</strong> 
           <div>
             语法: sin(double a) 
           </div> 
           <div>
             返回值: double 
           </div> 
           <div>
             说明: 返回a的正弦值 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select sin(0.8) from lxw_dual; 
           </div> 
           <div>
             0.7173560908995228 
           </div> <br> <strong>21. <span style="font-family:宋体">反正弦函数</span>: asin</strong> 
           <div>
             语法: asin(double a) 
           </div> 
           <div>
             返回值: double 
           </div> 
           <div>
             说明: 返回a的反正弦值 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select asin(0.7173560908995228) from lxw_dual; 
           </div> 
           <div>
             0.8 
           </div> <br> <strong>22. <span style="font-family:宋体">余弦函数</span>: cos</strong> 
           <div>
             语法: cos(double a) 
           </div> 
           <div>
             返回值: double 
           </div> 
           <div>
             说明: 返回a的余弦值 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select cos(0.9) from lxw_dual; 
           </div> 
           <div>
             0.6216099682706644 
           </div> <br> <strong>23. <span style="font-family:宋体">反余弦函数</span>: acos</strong> 
           <div>
             语法: acos(double a) 
           </div> 
           <div>
             返回值: double 
           </div> 
           <div>
             说明: 返回a的反余弦值 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select acos(0.6216099682706644) from lxw_dual; 
           </div> 
           <div>
             0.9 
           </div> <strong>24. positive<span style="font-family:宋体">函数</span>: positive</strong> 
           <div>
             语法: positive(int a), positive(double a) 
           </div> 
           <div>
             返回值: int double 
           </div> 
           <div>
             说明: 返回a 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select positive(-10) from lxw_dual; 
           </div> 
           <div>
             -10 
           </div> 
           <div>
             hive&gt; select positive(12) from lxw_dual; 
           </div> 
           <div>
             12 
           </div> <strong>25. negative<span style="font-family:宋体">函数</span>: negative</strong> 
           <div>
             语法: negative(int a), negative(double a) 
           </div> 
           <div>
             返回值: int double 
           </div> 
           <div>
             说明: 返回-a 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select negative(-5) from lxw_dual; 
           </div> 
           <div>
             5 
           </div> 
           <div>
             hive&gt; select negative(8) from lxw_dual; 
           </div> 
           <div>
             -8 
           </div> <strong><span style="font-family:宋体">五、日期函数</span>1. UNIX<span style="font-family:宋体">时间戳转日期函数</span>:from_unixtime</strong> 
           <div>
             语法: from_unixtime(bigint unixtime[, string format]) 
           </div> 
           <div>
             返回值: string 
           </div> 
           <div>
             说明: 转化UNIX时间戳（从1970-01-01 00:00:00 UTC到指定时间的秒数）到当前时区的时间格式 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select from_unixtime(1323308943,'yyyyMMdd') from lxw_dual; 
           </div> 
           <div>
             20111208 
           </div> <strong>2. <span style="font-family:宋体">获取当前</span>UNIX<span style="font-family:宋体">时间戳函数</span>:unix_timestamp</strong> 
           <div>
             语法: unix_timestamp() 
           </div> 
           <div>
             返回值: bigint 
           </div> 
           <div>
             说明: 获得当前时区的UNIX时间戳 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select unix_timestamp() from lxw_dual; 
           </div> 
           <div>
             1323309615 
           </div> <strong>3. <span style="font-family:宋体">日期转</span>UNIX<span style="font-family:宋体">时间戳函数</span>:unix_timestamp</strong> 
           <div>
             语法: unix_timestamp(string date) 
           </div> 
           <div>
             返回值: bigint 
           </div> 
           <div>
             说明: 转换格式为"yyyy-MM-ddHH:mm:ss"的日期到UNIX时间戳。如果转化失败，则返回0。 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select unix_timestamp('2011-12-07 13:01:03') from lxw_dual; 
           </div> 
           <div>
             1323234063 
           </div> <strong>4. <span style="font-family:宋体">指定格式日期转</span>UNIX<span style="font-family:宋体">时间戳函数</span>:unix_timestamp</strong> 
           <div>
             语法: unix_timestamp(string date, string pattern) 
           </div> 
           <div>
             返回值: bigint 
           </div> 
           <div>
             说明: 转换pattern格式的日期到UNIX时间戳。如果转化失败，则返回0。 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select unix_timestamp('20111207 13:01:03','yyyyMMddHH:mm:ss') from lxw_dual; 
           </div> 
           <div>
             1323234063 
           </div> <strong>5. <span style="font-family:宋体">日期时间转日期函数</span>:to_date</strong> 
           <div>
             语法: to_date(string timestamp) 
           </div> 
           <div>
             返回值: string 
           </div> 
           <div>
             说明: 返回日期时间字段中的日期部分。 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select to_date('2011-12-08 10:03:01') from lxw_dual; 
           </div> 
           <div>
             2011-12-08 
           </div> <br> <strong>6. <span style="font-family:宋体">日期转年函数</span>: year</strong> 
           <div>
             语法: year(string date) 
           </div> 
           <div>
             返回值: int 
           </div> 
           <div>
             说明: 返回日期中的年。 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select year('2011-12-08 10:03:01') from lxw_dual; 
           </div> 
           <div>
             2011 
           </div> 
           <div>
             hive&gt; select year('2012-12-08')from lxw_dual; 
           </div> 
           <div>
             2012 
           </div> <br> <strong>7. <span style="font-family:宋体">日期转月函数</span>: month</strong> 
           <div>
             语法: month (string date) 
           </div> 
           <div>
             返回值: int 
           </div> 
           <div>
             说明: 返回日期中的月份。 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select month('2011-12-08 10:03:01') from lxw_dual; 
           </div> 
           <div>
             12 
           </div> 
           <div>
             hive&gt; select month('2011-08-08')from lxw_dual; 
           </div> 
           <div>
             8 
           </div> <br> <strong>8. <span style="font-family:宋体">日期转天函数</span>: day</strong> 
           <div>
             语法: day (string date) 
           </div> 
           <div>
             返回值: int 
           </div> 
           <div>
             说明: 返回日期中的天。 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select day('2011-12-08 10:03:01') from lxw_dual; 
           </div> 
           <div>
             8 
           </div> 
           <div>
             hive&gt; select day('2011-12-24')from lxw_dual; 
           </div> 
           <div>
             24 
           </div> <br> <strong>9. <span style="font-family:宋体">日期转小时函数</span>: hour</strong> 
           <div>
             语法: hour (string date) 
           </div> 
           <div>
             返回值: int 
           </div> 
           <div>
             说明: 返回日期中的小时。 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select hour('2011-12-08 10:03:01') from lxw_dual; 
           </div> 
           <div>
             10 
           </div> <br> <strong>10. <span style="font-family:宋体">日期转分钟函数</span>: minute</strong> 
           <div>
             语法: minute (string date) 
           </div> 
           <div>
             返回值: int 
           </div> 
           <div>
             说明: 返回日期中的分钟。 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select minute('2011-12-08 10:03:01') from lxw_dual; 
           </div> 
           <div>
             3 
           </div> <br> <strong>11. <span style="font-family:宋体">日期转秒函数</span>: second</strong> 
           <div>
             语法: second (string date) 
           </div> 
           <div>
             返回值: int 
           </div> 
           <div>
             说明: 返回日期中的秒。 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select second('2011-12-08 10:03:01') from lxw_dual; 
           </div> 
           <div>
             1 
           </div> <br> <strong>12. <span style="font-family:宋体">日期转周函数</span>:weekofyear</strong> 
           <div>
             语法: weekofyear (string date) 
           </div> 
           <div>
             返回值: int 
           </div> 
           <div>
             说明: 返回日期在当前的周数。 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select weekofyear('2011-12-08 10:03:01') from lxw_dual; 
           </div> 
           <div>
             49 
           </div> <br> <strong>13. <span style="font-family:宋体">日期比较函数</span>: datediff</strong> 
           <div>
             语法: datediff(string enddate, string startdate) 
           </div> 
           <div>
             返回值: int 
           </div> 
           <div>
             说明: 返回结束日期减去开始日期的天数。 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select datediff('2012-12-08','2012-05-09')from lxw_dual; 
           </div> 
           <div>
             213 
           </div> <br> <strong>14. <span style="font-family:宋体">日期增加函数</span>: date_add</strong> 
           <div>
             语法: date_add(string startdate, int days) 
           </div> 
           <div>
             返回值: string 
           </div> 
           <div>
             说明: 返回开始日期startdate增加days天后的日期。 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select date_add('2012-12-08',10)from lxw_dual; 
           </div> 
           <div>
             2012-12-18 
           </div> <br> <strong>15. <span style="font-family:宋体">日期减少函数</span>: date_sub</strong> 
           <div>
             语法: date_sub (string startdate, int days) 
           </div> 
           <div>
             返回值: string 
           </div> 
           <div>
             说明: 返回开始日期startdate减少days天后的日期。 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select date_sub('2012-12-08',10)from lxw_dual; 
           </div> 
           <div>
             2012-11-28 
           </div> <br> <strong><span style="font-family:宋体">六、条件函数</span>1. If<span style="font-family:宋体">函数</span>: if</strong> 
           <div>
             语法: if(boolean testCondition, T valueTrue, T valueFalseOrNull) 
           </div> 
           <div>
             返回值: T 
           </div> 
           <div>
             说明:&nbsp;&nbsp;当条件testCondition为TRUE时，返回valueTrue；否则返回valueFalseOrNull 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select if(1=2,100,200) from lxw_dual; 
           </div> 
           <div>
             200 
           </div> 
           <div>
             hive&gt; select if(1=1,100,200) from lxw_dual; 
           </div> 
           <div>
             100 
           </div> <br> <strong>2. <span style="font-family:宋体">非空查找函数</span>: COALESCE</strong> 
           <div>
             语法: COALESCE(T v1, T v2, …) 
           </div> 
           <div>
             返回值: T 
           </div> 
           <div>
             说明:&nbsp;&nbsp;返回参数中的第一个非空值；如果所有值都为NULL，那么返回NULL 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select COALESCE(null,'100','50′) from lxw_dual; 
           </div> 
           <div>
             100 
           </div> <br> <strong>3. <span style="font-family:宋体">条件判断函数：</span>CASE</strong> 
           <div>
             语法: CASE a WHEN b THEN c [WHEN d THEN e]* [ELSE f] END 
           </div> 
           <div>
             返回值: T 
           </div> 
           <div>
             说明：如果a等于b，那么返回c；如果a等于d，那么返回e；否则返回f 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; Select case 100 when 50 then 'tom' when 100 then 'mary'else 'tim' end from lxw_dual; 
           </div> 
           <div>
             mary 
           </div> 
           <div>
             hive&gt; Select case 200 when 50 then 'tom' when 100 then 'mary'else 'tim' end from lxw_dual; 
           </div> 
           <div>
             tim 
           </div> <br> <strong>4. <span style="font-family:宋体">条件判断函数：</span>CASE</strong> 
           <div>
             语法: CASE WHEN a THEN b [WHEN c THEN d]* [ELSE e] END 
           </div> 
           <div>
             返回值: T 
           </div> 
           <div>
             说明：如果a为TRUE,则返回b；如果c为TRUE，则返回d；否则返回e 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select case when 1=2 then 'tom' when 2=2 then 'mary' else'tim' end from lxw_dual; 
           </div> 
           <div>
             mary 
           </div> 
           <div>
             hive&gt; select case when 1=1 then 'tom' when 2=2 then 'mary' else'tim' end from lxw_dual; 
           </div> 
           <div>
             tom 
           </div> <br> <strong><span style="font-family:宋体">七、字符串函数</span>1. <span style="font-family:宋体"> 字符串长度函数：</span>length</strong> 
           <div>
             语法: length(string A) 
           </div> 
           <div>
             返回值: int 
           </div> 
           <div>
             说明：返回字符串A的长度 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select length('abcedfg') from lxw_dual; 
           </div> 
           <div>
             7 
           </div> <br> <strong>2. <span style="font-family:宋体">字符串反转函数：</span>reverse</strong> 
           <div>
             语法: reverse(string A) 
           </div> 
           <div>
             返回值: string 
           </div> 
           <div>
             说明：返回字符串A的反转结果 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select reverse(abcedfg’) from lxw_dual; 
           </div> 
           <div>
             gfdecba 
           </div> <br> <strong>3. <span style="font-family:宋体">字符串连接函数：</span>concat</strong> 
           <div>
             语法: concat(string A, string B…) 
           </div> 
           <div>
             返回值: string 
           </div> 
           <div>
             说明：返回输入字符串连接后的结果，支持任意个输入字符串 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select concat(‘abc’,'def’,'gh’) from lxw_dual; 
           </div> 
           <div>
             abcdefgh 
           </div> <br> <strong>4. <span style="font-family:宋体">带分隔符字符串连接函数：</span>concat_ws</strong> 
           <div>
             语法: concat_ws(string SEP, string A, string B…) 
           </div> 
           <div>
             返回值: string 
           </div> 
           <div>
             说明：返回输入字符串连接后的结果，SEP表示各个字符串间的分隔符 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select concat_ws(',','abc','def','gh') from lxw_dual; 
           </div> 
           <div>
             abc,def,gh 
           </div> <br> <strong>5. <span style="font-family:宋体">字符串截取函数：</span>substr,substring</strong> 
           <div>
             语法: substr(string A, int start),substring(string A, int start) 
           </div> 
           <div>
             返回值: string 
           </div> 
           <div>
             说明：返回字符串A从start位置到结尾的字符串 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select substr('abcde',3) from lxw_dual; 
           </div> 
           <div>
             cde 
           </div> 
           <div>
             hive&gt; select substring('abcde',3) from lxw_dual; 
           </div> 
           <div>
             cde 
           </div> 
           <div>
             hive&gt;&nbsp;&nbsp;selectsubstr('abcde',-1) from lxw_dual;&nbsp;&nbsp;（和ORACLE相同） 
           </div> 
           <div>
             e 
           </div> <br> <strong>6. <span style="font-family:宋体">字符串截取函数：</span>substr,substring</strong> 
           <div>
             语法: substr(string A, int start, int len),substring(string A, intstart, int len) 
           </div> 
           <div>
             返回值: string 
           </div> 
           <div>
             说明：返回字符串A从start位置开始，长度为len的字符串 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select substr('abcde',3,2) from lxw_dual; 
           </div> 
           <div>
             cd 
           </div> 
           <div>
             hive&gt; select substring('abcde',3,2) from lxw_dual; 
           </div> 
           <div>
             cd 
           </div> 
           <div>
             hive&gt;select substring('abcde',-2,2) from lxw_dual; 
           </div> 
           <div>
             de 
           </div> <br> <strong>7. <span style="font-family:宋体">字符串转大写函数：</span>upper,ucase</strong> 
           <div>
             语法: upper(string A) ucase(string A) 
           </div> 
           <div>
             返回值: string 
           </div> 
           <div>
             说明：返回字符串A的大写格式 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select upper('abSEd') from lxw_dual; 
           </div> 
           <div>
             ABSED 
           </div> 
           <div>
             hive&gt; select ucase('abSEd') from lxw_dual; 
           </div> 
           <div>
             ABSED 
           </div> <br> <strong>8. <span style="font-family:宋体">字符串转小写函数：</span>lower,lcase</strong> 
           <div>
             语法: lower(string A) lcase(string A) 
           </div> 
           <div>
             返回值: string 
           </div> 
           <div>
             说明：返回字符串A的小写格式 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select lower('abSEd') from lxw_dual; 
           </div> 
           <div>
             absed 
           </div> 
           <div>
             hive&gt; select lcase('abSEd') from lxw_dual; 
           </div> 
           <div>
             absed 
           </div> <br> <strong>9. <span style="font-family:宋体">去空格函数：</span>trim</strong> 
           <div>
             语法: trim(string A) 
           </div> 
           <div>
             返回值: string 
           </div> 
           <div>
             说明：去除字符串两边的空格 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select trim(' abc ') from lxw_dual; 
           </div> 
           <div>
             abc 
           </div> <br> <strong>10. <span style="font-family:宋体">左边去空格函数：</span>ltrim</strong> 
           <div>
             语法: ltrim(string A) 
           </div> 
           <div>
             返回值: string 
           </div> 
           <div>
             说明：去除字符串左边的空格 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select ltrim(' abc ') from lxw_dual; 
           </div> 
           <div>
             abc 
           </div> <br> <strong>11. <span style="font-family:宋体">右边去空格函数：</span>rtrim</strong> 
           <div>
             语法: rtrim(string A) 
           </div> 
           <div>
             返回值: string 
           </div> 
           <div>
             说明：去除字符串右边的空格 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select rtrim(' abc ') from lxw_dual; 
           </div> 
           <div>
             abc 
           </div> <br> <strong>12. <span style="font-family:宋体">正则表达式替换函数：</span>regexp_replace</strong> 
           <div>
             语法: regexp_replace(string A, string B, string C) 
           </div> 
           <div>
             返回值: string 
           </div> 
           <div>
             说明：将字符串A中的符合java正则表达式B的部分替换为C。注意，在有些情况下要使用转义字符,类似oracle中的regexp_replace函数。 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select regexp_replace('foobar', 'oo|ar', '') from lxw_dual; 
           </div> 
           <div>
             fb 
           </div> <br> <strong>13. <span style="font-family:宋体">正则表达式解析函数：</span>regexp_extract</strong> 
           <div>
             语法: regexp_extract(string subject, string pattern, int index) 
           </div> 
           <div>
             返回值: string 
           </div> 
           <div>
             说明：将字符串subject按照pattern正则表达式的规则拆分，返回index指定的字符。 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select regexp_extract('foothebar', 'foo(.*?)(bar)', 1) fromlxw_dual; 
           </div> 
           <div>
             the 
           </div> 
           <div>
             hive&gt; select regexp_extract('foothebar', 'foo(.*?)(bar)', 2) fromlxw_dual; 
           </div> 
           <div>
             bar 
           </div> 
           <div>
             hive&gt; select regexp_extract('foothebar', 'foo(.*?)(bar)', 0) fromlxw_dual; 
           </div> 
           <div>
             foothebar 
           </div> 
           <div> 
            <strong>注意，在有些情况下要使用转义字符，下面的等号要用双竖线转义，这是java正则表达式的规则。</strong> 
           </div> 
           <div>
             select data_field, 
           </div> 
           <div>
             &nbsp; &nbsp;&nbsp;&nbsp;regexp_extract(data_field,'.*?bgStart\\=([^&amp;]+)',1) as aaa, 
           </div> 
           <div>
             &nbsp; &nbsp;&nbsp;&nbsp;regexp_extract(data_field,'.*?contentLoaded_headStart\\=([^&amp;]+)',1) as bbb, 
           </div> 
           <div>
             &nbsp; &nbsp;&nbsp;&nbsp;regexp_extract(data_field,'.*?AppLoad2Req\\=([^&amp;]+)',1) as ccc 
           </div> 
           <div>
             &nbsp; &nbsp;&nbsp;&nbsp;from pt_nginx_loginlog_st 
           </div> 
           <div>
             &nbsp; &nbsp;&nbsp;&nbsp;where pt = '2012-03-26'limit 2; 
           </div> <br> <strong>14. URL<span style="font-family:宋体">解析函数：</span>parse_url</strong> 
           <div>
             语法: parse_url(string urlString, string partToExtract [, stringkeyToExtract]) 
           </div> 
           <div>
             返回值: string 
           </div> 
           <div>
             说明：返回URL中指定的部分。partToExtract的有效值为：HOST, PATH, QUERY, REF, PROTOCOL, AUTHORITY, FILE, and USERINFO. 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; selectparse_url('http://facebook.com/path1/p.php?k1=v1&amp;k2=v2#Ref1', 'HOST') fromlxw_dual; 
           </div> 
           <div>
             facebook.com 
           </div> 
           <div>
             hive&gt; selectparse_url('http://facebook.com/path1/p.php?k1=v1&amp;k2=v2#Ref1', 'QUERY','k1') from lxw_dual; 
           </div> 
           <div>
             v1 
           </div> <strong>15. json<span style="font-family:宋体">解析函数：</span>get_json_object</strong> 
           <div>
             语法: get_json_object(string json_string, string path) 
           </div> 
           <div>
             返回值: string 
           </div> 
           <div>
             说明：解析json的字符串json_string,返回path指定的内容。如果输入的json字符串无效，那么返回NULL。 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select get_json_object('{"store": 
           </div> 
           <div>
             &gt;&nbsp;&nbsp;{"fruit":\[{"weight":8,"type":"apple"},{"weight":9,"type":"pear"}], 
           </div> 
           <div>
             &gt;&nbsp; &nbsp;"bicycle":{"price":19.95,"color":"red"} 
           </div> 
           <div>
             &gt;&nbsp; &nbsp;}, 
           </div> 
           <div>
             &gt; "email":"amy@only_for_json_udf_test.net", 
           </div> 
           <div>
             &gt;&nbsp;&nbsp;"owner":"amy" 
           </div> 
           <div>
             &gt; } 
           </div> 
           <div>
             &gt; ','$.owner') from lxw_dual; 
           </div> 
           <div>
             amy 
           </div> <br> <strong>16. <span style="font-family:宋体">空格字符串函数：</span>space</strong> 
           <div>
             语法: space(int n) 
           </div> 
           <div>
             返回值: string 
           </div> 
           <div>
             说明：返回长度为n的字符串 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select space(10) from lxw_dual; 
           </div> 
           <div>
             hive&gt; select length(space(10)) from lxw_dual; 
           </div> 
           <div>
             10 
           </div> <br> <strong>17. <span style="font-family:宋体">重复字符串函数：</span>repeat</strong> 
           <div>
             语法: repeat(string str, int n) 
           </div> 
           <div>
             返回值: string 
           </div> 
           <div>
             说明：返回重复n次后的str字符串 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select repeat('abc',5) from lxw_dual; 
           </div> 
           <div>
             abcabcabcabcabc 
           </div> <br> <strong>18. <span style="font-family:宋体">首字符</span>ascii<span style="font-family:宋体">函数：</span>ascii</strong> 
           <div>
             语法: ascii(string str) 
           </div> 
           <div>
             返回值: int 
           </div> 
           <div>
             说明：返回字符串str第一个字符的ascii码 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select ascii('abcde') from lxw_dual; 
           </div> 
           <div>
             97 
           </div> <br> <strong>19. <span style="font-family:宋体">左补足函数：</span>lpad</strong> 
           <div>
             语法: lpad(string str, int len, string pad) 
           </div> 
           <div>
             返回值: string 
           </div> 
           <div>
             说明：将str进行用pad进行左补足到len位 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select lpad('abc',10,'td') from lxw_dual; 
           </div> 
           <div>
             tdtdtdtabc 
           </div> 
           <div> 
            <strong>注意：与GP，ORACLE不同，pad 不能默认</strong> 
           </div> <br> <strong>20. <span style="font-family:宋体">右补足函数：</span>rpad</strong> 
           <div>
             语法: rpad(string str, int len, string pad) 
           </div> 
           <div>
             返回值: string 
           </div> 
           <div>
             说明：将str进行用pad进行右补足到len位 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select rpad('abc',10,'td') from lxw_dual; 
           </div> 
           <div>
             abctdtdtdt 
           </div> <br> <strong>21. <span style="font-family:宋体">分割字符串函数</span>: split</strong> 
           <div>
             语法:&nbsp;&nbsp;split(string str, stringpat) 
           </div> 
           <div>
             返回值:&nbsp;&nbsp;array 
           </div> 
           <div>
             说明: 按照pat字符串分割str，会返回分割后的字符串数组 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select split('abtcdtef','t') from lxw_dual; 
           </div> 
           <div>
             ["ab","cd","ef"] 
           </div> <br> <strong>22. <span style="font-family:宋体">集合查找函数</span>:find_in_set</strong> 
           <div>
             语法: find_in_set(string str, string strList) 
           </div> 
           <div>
             返回值: int 
           </div> 
           <div>
             说明: 返回str在strlist第一次出现的位置，strlist是用逗号分割的字符串。如果没有找该str字符，则返回0 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select find_in_set('ab','ef,ab,de') from lxw_dual; 
           </div> 
           <div>
             2 
           </div> 
           <div>
             hive&gt; select find_in_set('at','ef,ab,de') from lxw_dual; 
           </div> 
           <div>
             0 
           </div> <br> <strong><span style="font-family:宋体">八、集合统计函数</span>1. <span style="font-family:宋体"> 个数统计函数</span>: count</strong> 
           <div>
             语法: count(*), count(expr), count(DISTINCT expr[, expr_.]) 
           </div> 
           <div>
             返回值: int 
           </div> 
           <div>
             说明: count(*)统计检索出的行的个数，包括NULL值的行；count(expr)返回指定字段的非空值的个数；count(DISTINCTexpr[, expr_.])返回指定字段的不同的非空值的个数 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select count(*) from lxw_dual; 
           </div> 
           <div>
             20 
           </div> 
           <div>
             hive&gt; select count(distinct t) from lxw_dual; 
           </div> 
           <div>
             10 
           </div> <br> <strong>2. <span style="font-family:宋体">总和统计函数</span>: sum</strong> 
           <div>
             语法: sum(col), sum(DISTINCT col) 
           </div> 
           <div>
             返回值: double 
           </div> 
           <div>
             说明: sum(col)统计结果集中col的相加的结果；sum(DISTINCT col)统计结果中col不同值相加的结果 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select sum(t) from lxw_dual; 
           </div> 
           <div>
             100 
           </div> 
           <div>
             hive&gt; select sum(distinct t) from lxw_dual; 
           </div> 
           <div>
             70 
           </div> <br> <strong>3. <span style="font-family:宋体">平均值统计函数</span>: avg</strong> 
           <div>
             语法: avg(col), avg(DISTINCT col) 
           </div> 
           <div>
             返回值: double 
           </div> 
           <div>
             说明: avg(col)统计结果集中col的平均值；avg(DISTINCT col)统计结果中col不同值相加的平均值 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select avg(t) from lxw_dual; 
           </div> 
           <div>
             50 
           </div> 
           <div>
             hive&gt; select avg (distinct t) from lxw_dual; 
           </div> 
           <div>
             30 
           </div> <br> <strong>4. <span style="font-family:宋体">最小值统计函数</span>: min</strong> 
           <div>
             语法: min(col) 
           </div> 
           <div>
             返回值: double 
           </div> 
           <div>
             说明: 统计结果集中col字段的最小值 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select min(t) from lxw_dual; 
           </div> 
           <div>
             20 
           </div> <br> <strong>5. <span style="font-family:宋体">最大值统计函数</span>: max</strong> 
           <div>
             语法: maxcol) 
           </div> 
           <div>
             返回值: double 
           </div> 
           <div>
             说明: 统计结果集中col字段的最大值 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select max(t) from lxw_dual; 
           </div> 
           <div>
             120 
           </div> <br> <strong>6. <span style="font-family:宋体">非空集合总体变量函数</span>:var_pop</strong> 
           <div>
             语法: var_pop(col) 
           </div> 
           <div>
             返回值: double 
           </div> 
           <div>
             说明: 统计结果集中col非空集合的总体变量（忽略null） 
           </div> 
           <div>
             举例： 
           </div> <br> <strong>7. <span style="font-family:宋体">非空集合样本变量函数</span>:var_samp</strong> 
           <div>
             语法: var_samp (col) 
           </div> 
           <div>
             返回值: double 
           </div> 
           <div>
             说明: 统计结果集中col非空集合的样本变量（忽略null） 
           </div> 
           <div>
             举例： 
           </div> <br> <strong>8. <span style="font-family:宋体">总体标准偏离函数</span>:stddev_pop</strong> 
           <div>
             语法: stddev_pop(col) 
           </div> 
           <div>
             返回值: double 
           </div> 
           <div>
             说明: 该函数计算总体标准偏离，并返回总体变量的平方根，其返回值与VAR_POP函数的平方根相同 
           </div> 
           <div>
             举例： 
           </div> <br> <strong>9. <span style="font-family:宋体">样本标准偏离函数</span>:stddev_samp</strong> 
           <div>
             语法: stddev_samp (col) 
           </div> 
           <div>
             返回值: double 
           </div> 
           <div>
             说明: 该函数计算样本标准偏离 
           </div> 
           <div>
             举例： 
           </div> <br> <strong>10<span style="font-family:宋体">．中位数函数</span>:percentile</strong> 
           <div>
             语法: percentile(BIGINT col, p) 
           </div> 
           <div>
             返回值: double 
           </div> 
           <div>
             说明: 求准确的第pth个百分位数，p必须介于0和1之间，但是col字段目前只支持整数，不支持浮点数类型 
           </div> 
           <div>
             举例： 
           </div> <br> <strong>11. <span style="font-family:宋体">中位数函数</span>:percentile</strong> 
           <div>
             语法: percentile(BIGINT col, array(p1 [, p2]…)) 
           </div> 
           <div>
             返回值: array&lt;double&gt; 
           </div> 
           <div>
             说明: 功能和上述类似，之后后面可以输入多个百分位数，返回类型也为array&lt;double&gt;，其中为对应的百分位数。 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             select percentile(score,&lt;0.2,0.4&gt;) from lxw_dual；取0.2，0.4位置的数据 
           </div> <br> <strong>12. <span style="font-family:宋体">近似中位数函数</span>:percentile_approx</strong> 
           <div>
             语法: percentile_approx(DOUBLE col, p [, B]) 
           </div> 
           <div>
             返回值: double 
           </div> 
           <div>
             说明: 求近似的第pth个百分位数，p必须介于0和1之间，返回类型为double，但是col字段支持浮点类型。参数B控制内存消耗的近似精度，B越大，结果的准确度越高。默认为10,000。当col字段中的distinct值的个数小于B时，结果为准确的百分位数 
           </div> 
           <div>
             举例： 
           </div> <strong>13. <span style="font-family:宋体">近似中位数函数</span>:percentile_approx</strong> 
           <div>
             语法: percentile_approx(DOUBLE col, array(p1 [, p2]…) [, B]) 
           </div> 
           <div>
             返回值: array&lt;double&gt; 
           </div> 
           <div>
             说明: 功能和上述类似，之后后面可以输入多个百分位数，返回类型也为array&lt;double&gt;，其中为对应的百分位数。 
           </div> 
           <div>
             举例： 
           </div> <br> <strong>14. <span style="font-family:宋体">直方图</span>:histogram_numeric</strong> 
           <div>
             语法: histogram_numeric(col, b) 
           </div> 
           <div>
             返回值: array&lt;struct {‘x’,‘y’}&gt; 
           </div> 
           <div>
             说明: 以b为基准计算col的直方图信息。 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select histogram_numeric(100,5) from lxw_dual; 
           </div> 
           <div>
             [{"x":100.0,"y":1.0}] 
           </div> <br> <strong><span style="font-family:宋体">九、复合类型构建操作</span>1. Map<span style="font-family:宋体">类型构建</span>: map</strong> 
           <div>
             语法: map (key1, value1, key2, value2, …) 
           </div> 
           <div>
             说明：根据输入的key和value对构建map类型 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; Create table lxw_test as select map('100','tom','200','mary')as t from lxw_dual; 
           </div> 
           <div>
             hive&gt; describe lxw_test; 
           </div> 
           <div>
             t&nbsp; &nbsp;&nbsp; &nbsp;map&lt;string,string&gt; 
           </div> 
           <div>
             hive&gt; select t from lxw_test; 
           </div> 
           <div>
             {"100":"tom","200":"mary"} 
           </div> <br> <strong>2. Struct<span style="font-family:宋体">类型构建</span>: struct</strong> 
           <div>
             语法: struct(val1, val2, val3, …) 
           </div> 
           <div>
             说明：根据输入的参数构建结构体struct类型 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; create table lxw_test as select struct('tom','mary','tim')as t from lxw_dual; 
           </div> 
           <div>
             hive&gt; describe lxw_test; 
           </div> 
           <div>
             t&nbsp; &nbsp;&nbsp; &nbsp;struct&lt;col1:string,col2:string,col3:string&gt; 
           </div> 
           <div>
             hive&gt; select t from lxw_test; 
           </div> 
           <div>
             {"col1":"tom","col2":"mary","col3":"tim"} 
           </div> <br> <strong>3. array<span style="font-family:宋体">类型构建</span>: array</strong> 
           <div>
             语法: array(val1, val2, …) 
           </div> 
           <div>
             说明：根据输入的参数构建数组array类型 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; create table lxw_test as selectarray("tom","mary","tim") as t from lxw_dual; 
           </div> 
           <div>
             hive&gt; describe lxw_test; 
           </div> 
           <div>
             t&nbsp; &nbsp;&nbsp; &nbsp; array&lt;string&gt; 
           </div> 
           <div>
             hive&gt; select t from lxw_test; 
           </div> 
           <div>
             ["tom","mary","tim"] 
           </div> <br> <strong><span style="font-family:宋体">十、复杂类型访问操作</span>1. array<span style="font-family:宋体">类型访问</span>: A[n]</strong> 
           <div>
             语法: A[n] 
           </div> 
           <div>
             操作类型: A为array类型，n为int类型 
           </div> 
           <div>
             说明：返回数组A中的第n个变量值。数组的起始下标为0。比如，A是个值为['foo', 'bar']的数组类型，那么A[0]将返回'foo',而A[1]将返回'bar' 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; create table lxw_test as selectarray("tom","mary","tim") as t from lxw_dual; 
           </div> 
           <div>
             hive&gt; select t[0],t[1],t[2] from lxw_test; 
           </div> 
           <div>
             tom&nbsp; &nbsp;&nbsp;&nbsp;mary&nbsp; &nbsp; tim 
           </div> <br> <strong>2. map<span style="font-family:宋体">类型访问</span>: M[key]</strong> 
           <div>
             语法: M[key] 
           </div> 
           <div>
             操作类型: M为map类型，key为map中的key值 
           </div> 
           <div>
             说明：返回map类型M中，key值为指定值的value值。比如，M是值为{'f' -&gt; 'foo', 'b'-&gt; 'bar', 'all' -&gt; 'foobar'}的map类型，那么M['all']将会返回'foobar' 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; Create table lxw_test as selectmap('100','tom','200','mary') as t from lxw_dual; 
           </div> 
           <div>
             hive&gt; select t['200'],t['100'] from lxw_test; 
           </div> 
           <div>
             mary&nbsp; &nbsp; tom 
           </div> <br> <strong>3. struct<span style="font-family:宋体">类型访问</span>: S.x</strong> 
           <div>
             语法: S.x 
           </div> 
           <div>
             操作类型: S为struct类型 
           </div> 
           <div>
             说明：返回结构体S中的x字段。比如，对于结构体struct foobar {int foo, int bar}，foobar.foo返回结构体中的foo字段 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; create table lxw_test as select struct('tom','mary','tim')as t from lxw_dual; 
           </div> 
           <div>
             hive&gt; describe lxw_test; 
           </div> 
           <div>
             t&nbsp; &nbsp;&nbsp; &nbsp;struct&lt;col1:string,col2:string,col3:string&gt; 
           </div> 
           <div>
             hive&gt; select t.col1,t.col3 from lxw_test; 
           </div> 
           <div>
             tom&nbsp; &nbsp;&nbsp;&nbsp;tim 
           </div> <br> <strong><span style="font-family:宋体">十一、复杂类型长度统计函数</span>1.&nbsp; &nbsp; Map<span style="font-family:宋体">类型长度函数</span>: size(Map&lt;K.V&gt;)</strong> 
           <div>
             语法: size(Map&lt;K.V&gt;) 
           </div> 
           <div>
             返回值: int 
           </div> 
           <div>
             说明: 返回map类型的长度 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select size(map('100','tom','101','mary')) from lxw_dual; 
           </div> 
           <div>
             2 
           </div> <br> <strong>2.&nbsp; &nbsp; array<span style="font-family:宋体">类型长度函数</span>: size(Array&lt;T&gt;)</strong> 
           <div>
             语法: size(Array&lt;T&gt;) 
           </div> 
           <div>
             返回值: int 
           </div> 
           <div>
             说明: 返回array类型的长度 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select size(array('100','101','102','103')) from lxw_dual; 
           </div> 
           <div>
             4 
           </div> <br> <strong>3.&nbsp; &nbsp; <span style="font-family:宋体">类型转换函数</span></strong> 
           <div>
             类型转换函数: cast 
           </div> 
           <div>
             语法: cast(expr as &lt;type&gt;) 
           </div> 
           <div>
             返回值: Expected "=" to follow "type" 
           </div> 
           <div>
             说明: 返回array类型的长度 
           </div> 
           <div>
             举例： 
           </div> 
           <div>
             hive&gt; select cast(1 as bigint) from lxw_dual; 
           </div> </td> 
         </tr> 
        </tbody> 
       </table> 
      </div> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

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