Hive基础sql语法(DML)

缺乏、安全感 2022-05-22 12:24 172阅读 0赞

#### DML操作(Data Manipulation Language) ####

*参考官方文档：* [DML文档][DML]

*  因update和delete在Hive中一般用不到，本篇文章不做讲解。本文主要介绍Load和insert操作。

##### 1. LOAD（加载数据） #####

LOAD作用是加载文件到表中（Loading files into tables）  
\* 下面是官网上为我们列出的语法：

LOAD DATA [LOCAL] INPATH 'filepath' [OVERWRITE] INTO TABLE tablename [PARTITION (partcol1=val1, partcol2=val2 ...)] LOAD DATA [LOCAL] INPATH 'filepath' [OVERWRITE] INTO TABLE tablename [PARTITION (partcol1=val1, partcol2=val2 ...)] [INPUTFORMAT 'inputformat' SERDE 'serde'] (3.0 or later)

*  1.加载数据到表中时，Hive不做任何转换。加载操作只是把数据拷贝或移动操作，即移动数据文件到Hive表相应的位置。
 *  2.加载的目标可以是一个表，也可以是一个分区。如果表是分区的，则必须通过指定所有分区列的值来指定一个表的分区。
 *  3.filepath可以是一个文件，也可以是一个目录。不管什么情况下，filepath被认为是一个文件集合。

**LOCAL**：表示输入文件在本地文件系统（Linux），如果没有加LOCAL，hive则会去HDFS上查找该文件。  
**OVERWRITE**：表示如果表中有数据，则先删除数据，再插入新数据，如果没有这个关键词，则直接附加数据到表中。  
**PARTITION**：如果表中存在分区，可以按照分区进行导入。

# 创建一张员工表
    hive> create table emp 
        > (empno int, ename string, job string, mgr int, hiredate string, salary double, comm double, deptno int)
        > ROW FORMAT DELIMITED 
        > FIELDS TERMINATED BY '\t' ;
    OK
    Time taken: 0.651 seconds
    # 把本地文件系统中emp.txt导入表
    hive> LOAD DATA LOCAL INPATH '/home/hadoop/emp.txt' OVERWRITE INTO TABLE emp; 
    Loading data to table default.emp
    Table default.emp stats: [numFiles=1, numRows=0, totalSize=886, rawDataSize=0]
    OK
    Time taken: 1.848 seconds
    # 查看表数据
    hive> select * from emp;
    OK
    7369    SMITH   CLERK   7902    1980-12-17      800.0   NULL    20
    7499    ALLEN   SALESMAN        7698    1981-2-20       1600.0  300.0   30
    7521    WARD    SALESMAN        7698    1981-2-22       1250.0  500.0   30
    7566    JONES   MANAGER 7839    1981-4-2        2975.0  NULL    20
    7654    MARTIN  SALESMAN        7698    1981-9-28       1250.0  1400.0  30
    7698    BLAKE   MANAGER 7839    1981-5-1        2850.0  NULL    30
    7782    CLARK   MANAGER 7839    1981-6-9        2450.0  NULL    10
    7788    SCOTT   ANALYST 7566    1987-4-19       3000.0  NULL    20
    7839    KING    PRESIDENT       NULL    1981-11-17      5000.0  NULL    10
    7844    TURNER  SALESMAN        7698    1981-9-8        1500.0  0.0     30
    7876    ADAMS   CLERK   7788    1987-5-23       1100.0  NULL    20
    7900    JAMES   CLERK   7698    1981-12-3       950.0   NULL    30
    7902    FORD    ANALYST 7566    1981-12-3       3000.0  NULL    20
    7934    MILLER  CLERK   7782    1982-1-23       1300.0  NULL    10
    # 不用OVERWRITE关键字
    hive>  LOAD DATA LOCAL INPATH '/home/hadoop/emp.txt' INTO TABLE emp;
    # 再次查看
    hive> select * from emp;
    OK
    7369    SMITH   CLERK   7902    1980-12-17      800.0   NULL    20
    7499    ALLEN   SALESMAN        7698    1981-2-20       1600.0  300.0   30
    7521    WARD    SALESMAN        7698    1981-2-22       1250.0  500.0   30
    7566    JONES   MANAGER 7839    1981-4-2        2975.0  NULL    20
    7654    MARTIN  SALESMAN        7698    1981-9-28       1250.0  1400.0  30
    7698    BLAKE   MANAGER 7839    1981-5-1        2850.0  NULL    30
    7782    CLARK   MANAGER 7839    1981-6-9        2450.0  NULL    10
    7788    SCOTT   ANALYST 7566    1987-4-19       3000.0  NULL    20
    7839    KING    PRESIDENT       NULL    1981-11-17      5000.0  NULL    10
    7844    TURNER  SALESMAN        7698    1981-9-8        1500.0  0.0     30
    7876    ADAMS   CLERK   7788    1987-5-23       1100.0  NULL    20
    7900    JAMES   CLERK   7698    1981-12-3       950.0   NULL    30
    7902    FORD    ANALYST 7566    1981-12-3       3000.0  NULL    20
    7934    MILLER  CLERK   7782    1982-1-23       1300.0  NULL    10
    7369    SMITH   CLERK   7902    1980-12-17      800.0   NULL    20
    7499    ALLEN   SALESMAN        7698    1981-2-20       1600.0  300.0   30
    7521    WARD    SALESMAN        7698    1981-2-22       1250.0  500.0   30
    7566    JONES   MANAGER 7839    1981-4-2        2975.0  NULL    20
    7654    MARTIN  SALESMAN        7698    1981-9-28       1250.0  1400.0  30
    7698    BLAKE   MANAGER 7839    1981-5-1        2850.0  NULL    30
    7782    CLARK   MANAGER 7839    1981-6-9        2450.0  NULL    10
    7788    SCOTT   ANALYST 7566    1987-4-19       3000.0  NULL    20
    7839    KING    PRESIDENT       NULL    1981-11-17      5000.0  NULL    10
    7844    TURNER  SALESMAN        7698    1981-9-8        1500.0  0.0     30
    7876    ADAMS   CLERK   7788    1987-5-23       1100.0  NULL    20
    7900    JAMES   CLERK   7698    1981-12-3       950.0   NULL    30
    7902    FORD    ANALYST 7566    1981-12-3       3000.0  NULL    20
    7934    MILLER  CLERK   7782    1982-1-23       1300.0  NULL    10
    Time taken: 0.137 seconds, Fetched: 28 row(s)
    # 再次OVERWRITE覆盖导入
    hive> LOAD DATA LOCAL INPATH '/home/hadoop/emp.txt' OVERWRITE INTO TABLE emp; 
    # 发现数据被覆盖了
    hive> select * from emp;
    OK
    7369    SMITH   CLERK   7902    1980-12-17      800.0   NULL    20
    7499    ALLEN   SALESMAN        7698    1981-2-20       1600.0  300.0   30
    7521    WARD    SALESMAN        7698    1981-2-22       1250.0  500.0   30
    7566    JONES   MANAGER 7839    1981-4-2        2975.0  NULL    20
    7654    MARTIN  SALESMAN        7698    1981-9-28       1250.0  1400.0  30
    7698    BLAKE   MANAGER 7839    1981-5-1        2850.0  NULL    30
    7782    CLARK   MANAGER 7839    1981-6-9        2450.0  NULL    10
    7788    SCOTT   ANALYST 7566    1987-4-19       3000.0  NULL    20
    7839    KING    PRESIDENT       NULL    1981-11-17      5000.0  NULL    10
    7844    TURNER  SALESMAN        7698    1981-9-8        1500.0  0.0     30
    7876    ADAMS   CLERK   7788    1987-5-23       1100.0  NULL    20
    7900    JAMES   CLERK   7698    1981-12-3       950.0   NULL    30
    7902    FORD    ANALYST 7566    1981-12-3       3000.0  NULL    20
    7934    MILLER  CLERK   7782    1982-1-23       1300.0  NULL    10
    Time taken: 0.164 seconds, Fetched: 14 row(s)

##### 2. insert into到表（Inserting data into Hive Tables from queries） #####

*  下面是官网上为我们列出的语法：

Standard syntax:
    INSERT OVERWRITE TABLE tablename1 [PARTITION (partcol1=val1, partcol2=val2 ...) [IF NOT EXISTS]] select_statement1 FROM from_statement;
    INSERT INTO TABLE tablename1 [PARTITION (partcol1=val1, partcol2=val2 ...)] select_statement1 FROM from_statement;
    
    Hive extension (multiple inserts):
    FROM from_statement
    INSERT OVERWRITE TABLE tablename1 [PARTITION (partcol1=val1, partcol2=val2 ...) [IF NOT EXISTS]] select_statement1 [INSERT OVERWRITE TABLE tablename2 [PARTITION ... [IF NOT EXISTS]] select_statement2] [INSERT INTO TABLE tablename2 [PARTITION ...] select_statement2] ...;
    FROM from_statement
    INSERT INTO TABLE tablename1 [PARTITION (partcol1=val1, partcol2=val2 ...)] select_statement1 [INSERT INTO TABLE tablename2 [PARTITION ...] select_statement2] [INSERT OVERWRITE TABLE tablename2 [PARTITION ... [IF NOT EXISTS]] select_statement2] ...;
    
    Hive extension (dynamic partition inserts):
    INSERT OVERWRITE TABLE tablename PARTITION (partcol1[=val1], partcol2[=val2] ...) select_statement FROM from_statement;
    INSERT INTO TABLE tablename PARTITION (partcol1[=val1], partcol2[=val2] ...) select_statement FROM from_statement;

官网又给我们列出一大堆语法，看着就很可怕，但是仔细整理后再来看看你会发现并没有什么，下面对其进行分析：

*  1 标准语法（Standard syntax）：INSERT OVERWRITE TABLE tablename1 select\_statement1 FROM from\_statement; 其实就是一个简单的插入语句。
 *  2.可以使用PARTITION 关键字，进行分区插入。
 *  3.OVERWRITE是否选择覆盖。
 *  4 使用插入语法会跑mr作业。
 *  5 multiple inserts：代表多行插入。
 *  6 dynamic partition inserts：动态分区插入。

**注：**这里有两种插语法，也就是加上OVERWRITE关键字和不加的区别。

# insert overwrite
    hive> insert overwrite table emp2 select * from emp;
    Query ID = hadoop_20180624141010_3063d504-ff2f-4003-843f-7dca60f1dd7e
    Total jobs = 3
    Launching Job 1 out of 3
    ...
    OK
    Time taken: 19.554 seconds
    hive> select * from emp2;
    OK
    7369    SMITH   CLERK   7902    1980-12-17      800.0   NULL    20
    7499    ALLEN   SALESMAN        7698    1981-2-20       1600.0  300.0   30
    7521    WARD    SALESMAN        7698    1981-2-22       1250.0  500.0   30
    7566    JONES   MANAGER 7839    1981-4-2        2975.0  NULL    20
    7654    MARTIN  SALESMAN        7698    1981-9-28       1250.0  1400.0  30
    7698    BLAKE   MANAGER 7839    1981-5-1        2850.0  NULL    30
    7782    CLARK   MANAGER 7839    1981-6-9        2450.0  NULL    10
    7788    SCOTT   ANALYST 7566    1987-4-19       3000.0  NULL    20
    7839    KING    PRESIDENT       NULL    1981-11-17      5000.0  NULL    10
    7844    TURNER  SALESMAN        7698    1981-9-8        1500.0  0.0     30
    7876    ADAMS   CLERK   7788    1987-5-23       1100.0  NULL    20
    7900    JAMES   CLERK   7698    1981-12-3       950.0   NULL    30
    7902    FORD    ANALYST 7566    1981-12-3       3000.0  NULL    20
    7934    MILLER  CLERK   7782    1982-1-23       1300.0  NULL    10
    Time taken: 0.143 seconds, Fetched: 14 row(s)
    
    # insert追加
    hive> insert into table emp2 select * from emp;
    Query ID = hadoop_20180624141010_3063d504-ff2f-4003-843f-7dca60f1dd7e
    Total jobs = 3
    ...
    OK
    Time taken: 18.539 seconds
    hive> select * from emp2;
    OK
    7369    SMITH   CLERK   7902    1980-12-17      800.0   NULL    20
    7499    ALLEN   SALESMAN        7698    1981-2-20       1600.0  300.0   30
    7521    WARD    SALESMAN        7698    1981-2-22       1250.0  500.0   30
    7566    JONES   MANAGER 7839    1981-4-2        2975.0  NULL    20
    7654    MARTIN  SALESMAN        7698    1981-9-28       1250.0  1400.0  30
    7698    BLAKE   MANAGER 7839    1981-5-1        2850.0  NULL    30
    7782    CLARK   MANAGER 7839    1981-6-9        2450.0  NULL    10
    7788    SCOTT   ANALYST 7566    1987-4-19       3000.0  NULL    20
    7839    KING    PRESIDENT       NULL    1981-11-17      5000.0  NULL    10
    7844    TURNER  SALESMAN        7698    1981-9-8        1500.0  0.0     30
    7876    ADAMS   CLERK   7788    1987-5-23       1100.0  NULL    20
    7900    JAMES   CLERK   7698    1981-12-3       950.0   NULL    30
    7902    FORD    ANALYST 7566    1981-12-3       3000.0  NULL    20
    7934    MILLER  CLERK   7782    1982-1-23       1300.0  NULL    10
    7369    SMITH   CLERK   7902    1980-12-17      800.0   NULL    20
    7499    ALLEN   SALESMAN        7698    1981-2-20       1600.0  300.0   30
    7521    WARD    SALESMAN        7698    1981-2-22       1250.0  500.0   30
    7566    JONES   MANAGER 7839    1981-4-2        2975.0  NULL    20
    7654    MARTIN  SALESMAN        7698    1981-9-28       1250.0  1400.0  30
    7698    BLAKE   MANAGER 7839    1981-5-1        2850.0  NULL    30
    7782    CLARK   MANAGER 7839    1981-6-9        2450.0  NULL    10
    7788    SCOTT   ANALYST 7566    1987-4-19       3000.0  NULL    20
    7839    KING    PRESIDENT       NULL    1981-11-17      5000.0  NULL    10
    7844    TURNER  SALESMAN        7698    1981-9-8        1500.0  0.0     30
    7876    ADAMS   CLERK   7788    1987-5-23       1100.0  NULL    20
    7900    JAMES   CLERK   7698    1981-12-3       950.0   NULL    30
    7902    FORD    ANALYST 7566    1981-12-3       3000.0  NULL    20
    7934    MILLER  CLERK   7782    1982-1-23       1300.0  NULL    10
    Time taken: 0.132 seconds, Fetched: 28 row(s)

*  Inserting values into tables（手动插入一条或多条记录，会跑mr作业 不常用）
 *  官方用法：

INSERT INTO TABLE tablename [PARTITION (partcol1[=val1], partcol2[=val2] ...)] VALUES values_row [, values_row ...]

hive> create table stu(
        > id int,
        > name string
        > )
        >  ROW FORMAT DELIMITED FIELDS TERMINATED BY '\t';
    OK
    Time taken: 0.253 seconds
    hive> insert into table stu values (1,"zhangsan");
    Query ID = hadoop_20180624141010_3063d504-ff2f-4003-843f-7dca60f1dd7e
    Total jobs = 3
    ...
    OK
    Time taken: 16.589 seconds
    hive> select * from stu;
    OK
    1       zhangsan
    Time taken: 0.123 seconds, Fetched: 1 row(s)

##### 3. 数据导出（Writing data into the filesystem from queries） #####

查询结果可以通过语句插入文件系统中：  
\* 下面是官网上为我们列出的语法：

Standard syntax:（标准语法）
    INSERT OVERWRITE [LOCAL] DIRECTORY directory1 [ROW FORMAT row_format] [STORED AS file_format] (Note: Only available starting with Hive 0.11.0) SELECT ... FROM ... Hive extension (multiple inserts):（导出多条记录） FROM from_statement INSERT OVERWRITE [LOCAL] DIRECTORY directory1 select_statement1 [INSERT OVERWRITE [LOCAL] DIRECTORY directory2 select_statement2] ... row_format : DELIMITED [FIELDS TERMINATED BY char [ESCAPED BY char]] [COLLECTION ITEMS TERMINATED BY char] [MAP KEYS TERMINATED BY char] [LINES TERMINATED BY char] [NULL DEFINED AS char] (Note: Only available starting with Hive 0.13)

**LOCAL**：加上LOCAL关键字代表导入本地系统，不加默认导入HDFS；  
**STORED AS**:可以指定存储格式。

hive> insert overwrite local directory '/home/hadoop/stu' ROW FORMAT DELIMITED FIELDS TERMINATED BY '\t' select * from stu;
    Query ID = hadoop_20180624153131_97271014-abcf-4e70-b318-7de85d27c97f
    Total jobs = 1
    ...
    OK
    Time taken: 15.09 seconds
    # 结果
    [hadoop@hadoop000 stu]$ pwd
    /home/hadoop/stu
    [hadoop@hadoop000 stu]$ cat 000000_0 
    1       zhangsan
    
    # 导出多条记录
    hive> from emp
        > INSERT OVERWRITE  LOCAL DIRECTORY '/home/hadoop/tmp/hivetmp1'
        > ROW FORMAT DELIMITED FIELDS TERMINATED BY "\t"
        > select empno, ename  
        > INSERT OVERWRITE  LOCAL DIRECTORY '/home/hadoop/tmp/hivetmp2'
        > ROW FORMAT DELIMITED FIELDS TERMINATED BY "\t"
        > select ename;
    Query ID = hadoop_20180624153131_97271014-abcf-4e70-b318-7de85d27c97f
    Total jobs = 1
    ...
    OK
    Time taken: 16.261 seconds
    # 结果
    [hadoop@hadoop000 tmp]$ cd hivetmp1
    [hadoop@hadoop000 hivetmp1]$ ll
    total 4
    -rw-r--r-- 1 hadoop hadoop 154 Jun 24 15:39 000000_0
    [hadoop@hadoop000 hivetmp1]$ cat 000000_0 
    7369    SMITH
    7499    ALLEN
    7521    WARD
    7566    JONES
    7654    MARTIN
    7698    BLAKE
    7782    CLARK
    7788    SCOTT
    7839    KING
    7844    TURNER
    7876    ADAMS
    7900    JAMES
    7902    FORD
    7934    MILLER
    [hadoop@hadoop000 hivetmp1]$ cd ..
    [hadoop@hadoop000 tmp]$ cd hivetmp2
    [hadoop@hadoop000 hivetmp2]$ cat 000000_0 
    SMITH
    ALLEN
    WARD
    JONES
    MARTIN
    BLAKE
    CLARK
    SCOTT
    KING
    TURNER
    ADAMS
    JAMES
    FORD
    MILLER

*参考：* [https://blog.csdn.net/yu0\_zhang0/article/details/79007784][https_blog.csdn.net_yu0_zhang0_article_details_79007784]

[DML]: https://cwiki.apache.org/confluence/display/Hive/LanguageManual+DML
[https_blog.csdn.net_yu0_zhang0_article_details_79007784]: https://blog.csdn.net/yu0_zhang0/article/details/79007784