hive中创建hive-json格式的表及查询

﹏ヽ暗。殇╰゛Y 2022-01-11 03:29 289阅读 0赞

**在hive中对于json的数据格式，可以使用get\_json\_object或json\_tuple先解析然后查询。**

**也可以直接在hive中创建json格式的表结构，这样就可以直接查询，实战如下(hive-2.3.0版本)：**

**1. 准备数据源**

将以下内容保存为test.txt

{"student":{"name":"king","age":11,"sex":"M"},"class":{"book":"语文","level":2,"score":80},"teacher":{"name":"t1","class":"语文"}}
    {"student":{"name":"wang","age":12,"sex":"M"},"class":{"book":"语文","level":2,"score":80},"teacher":{"name":"t1","class":"语文"}}
    {"student":{"name":"test","age":13,"sex":"M"},"class":{"book":"语文","level":2,"score":80},"teacher":{"name":"t1","class":"语文"}}
    {"student":{"name":"test2","age":14,"sex":"M"},"class":{"book":"语文","level":2,"score":80},"teacher":{"name":"t1","class":"语文"}}
    {"student":{"name":"test3","age":15,"sex":"M"},"class":{"book":"语文","level":2,"score":80},"teacher":{"name":"t1","class":"语文"}}
    {"student":{"name":"test4","age":16,"sex":"M"},"class":{"book":"语文","level":2,"score":80},"teacher":{"name":"t1","class":"语文"}}

**2. 创建hive表**

注意serde格式大小写不能写错： **org.apache.hive.hcatalog.data.JsonSerDe**

create external table if not exists dw_stg.student(
    student map<string,string> comment "学生信息",
    class map<string,string> comment "课程信息",
    teacher map<string,string> comment "授课老师信息"
    )
    comment "学生课程信息"
    row format serde 'org.apache.hive.hcatalog.data.JsonSerDe'
    stored as textfile;

**3. 上传数据**

将test.txt上传到刚才创建的student目录

hdfs dfs -put test.txt /user/hive/warehouse/dw_stg.db/student/

**4. 使用hql查询**

**查询所有信息记录：**

**![367203-20180119180549912-1814283235.png][]**

查询字段student信息

![367203-20180119180631474-1144537379.png][]

查询字段class信息

![367203-20180119180712740-826945525.png][]

查询学生姓名为test4的所有记录

![367203-20180119192614740-949737723.png][]

取json串中某个值可以使用 student\['name'\] ，如下：

select 
        student['name'] as stuName,
        class['book'] as cls_book, 
        class['score'] as cls_score,
        teacher['name'] as tech_name 
    from student 
    where student['name'] = 'test4';

![367203-20180119192903896-765810843.png][]

总体看起来，比使用**get\_json\_object或json\_tuple**解析方便多了**。**

[367203-20180119180549912-1814283235.png]: /images/20220111/96a53c5b781541918778ed0a5a85fe13.png
[367203-20180119180631474-1144537379.png]: /images/20220111/717437a4e578439485cbc87a54b8e0c4.png
[367203-20180119180712740-826945525.png]: /images/20220111/d7acde96b09a4a3eacbb3658cfabc20f.png
[367203-20180119192614740-949737723.png]: /images/20220111/b4ce8f54ca3c4f7c8a381ae2882aa93c.png
[367203-20180119192903896-765810843.png]: /images/20220111/83983325d4c54fb98a8b849e42474fc9.png