zoukankan      html  css  js  c++  java
  • ORACLE GROUPING函数的使用

    GROUPING函数可以接受一列,返回0或者1。如果列值为空,那么GROUPING()返回1;如果列值非空,那么返回0。GROUPING只能在使用ROLLUP或CUBE的查询中使用。当需要在返回空值的地方显示某个值时,GROUPING()就非常有用。

    1、在ROLLUP中对单列使用GROUPING()

    SQL> select division_id,sum(salary)
    2 from employees2
    3 group by rollup(division_id)
    4 order by division_id;
    DIV SUM(SALARY)
    --- -----------
    BUS 1610000
    OPE 1320000
    SAL 4936000
    SUP 1015000
    8881000

    加上GROUPING来看看

    SQL> select grouping(division_id),division_id,sum(salary)
    2 from employees2
    3 group by rollup(division_id)
    4 order by division_id;
    GROUPING(DIVISION_ID) DIV SUM(SALARY)
    --------------------- --- -----------
    0 BUS 1610000
    0 OPE 1320000
    0 SAL 4936000
    0 SUP 1015000
    1 8881000

    可以看到,为空的地方返回1,非空的地方返回0。


    2、使用CASE转换GROUPING()的返回值
    可能你会觉得前面的0和1太枯燥了,代表不了任何意义,说白了就是不够人性化,呵呵。这个时候我们可以使用CASE来转换为一些有意义的值。

    SQL> select
    2 case grouping(division_id)
    3 when 1 then 'all divisions'
    4 else division_id
    5 end as div,
    6 sum(salary)
    7 from employees2
    8 group by rollup(division_id)
    9 order by division_id;
    DIV SUM(SALARY)
    ------------- -----------
    BUS 1610000
    OPE 1320000
    SAL 4936000
    SUP 1015000
    all divisions 8881000

    3、使用CASE和GROUPING()转换多个列的值

    SQL> select
    2 case grouping(division_id)
    3 when 1 then 'all divisions'
    4 else division_id
    5 end as div,
    6 case grouping(job_id)
    7 when 1 then 'all jobs'
    8 else job_id
    9 end as job,
    10 sum(salary)
    11 from employees2
    12 group by rollup(division_id,job_id)
    13 order by division_id,job_id;
    DIV JOB SUM(SALARY)
    ------------- -------- -----------
    BUS MGR 530000
    BUS PRE 800000
    BUS WOR 280000
    BUS all jobs 1610000
    OPE ENG 245000
    OPE MGR 805000
    OPE WOR 270000
    OPE all jobs 1320000
    SAL MGR 4446000
    SAL WOR 490000
    SAL all jobs 4936000
    DIV JOB SUM(SALARY)
    ------------- -------- -----------
    SUP MGR 465000
    SUP TEC 115000
    SUP WOR 435000
    SUP all jobs 1015000
    all divisions all jobs 8881000
    16 rows selected.

    4、CUBE与GROUPING()结合使用

    SQL> select
    2 case grouping(division_id)
    3 when 1 then 'all divisions'
    4 else division_id
    5 end as div,
    6 case grouping(job_id)
    7 when 1 then 'all jobs'
    8 else job_id
    9 end as job,
    10 sum(salary)
    11 from employees2
    12 group by cube(division_id,job_id)
    13 order by division_id,job_id;
    DIV JOB SUM(SALARY)
    ------------- -------- -----------
    BUS MGR 530000
    BUS PRE 800000
    BUS WOR 280000
    BUS all jobs 1610000
    OPE ENG 245000
    OPE MGR 805000
    OPE WOR 270000
    OPE all jobs 1320000
    SAL MGR 4446000
    SAL WOR 490000
    SAL all jobs 4936000
    DIV JOB SUM(SALARY)
    ------------- -------- -----------
    SUP MGR 465000
    SUP TEC 115000
    SUP WOR 435000
    SUP all jobs 1015000
    all divisions ENG 245000
    all divisions MGR 6246000
    all divisions PRE 800000
    all divisions TEC 115000
    all divisions WOR 1475000
    all divisions all jobs 8881000
    21 rows selected.

    5、使用GROUPING SETS子句
    使用GROUPING SETS子句可以只返回小计记录。

    SQL> select division_id,job_id,sum(salary)
    2 from employees2
    3 group by grouping sets(division_id,job_id)
    4 order by division_id,job_id;
    DIV JOB SUM(SALARY)
    --- --- -----------
    BUS 1610000
    OPE 1320000
    SAL 4936000
    SUP 1015000
    ENG 245000
    MGR 6246000
    PRE 800000
    TEC 115000
    WOR 1475000
    9 rows selected.
  • 相关阅读:
    MongoDB索引实战技巧
    解决scp/ssh提示输密码慢问题
    mac系统忘记root密码的解决办法
    Javascript DataGrid using the MVC
    便捷的安全检测
    北京出现NW28开头假钞 天津已有相同案例
    12月编程语言排行榜:C#前途无量
    实时股票数据接口大全
    [一定要看完]住在隔壁的刚毕业的大学生小夫妻
    [行業]金山卫士宣布开源 用透明对抗360
  • 原文地址:https://www.cnblogs.com/iImax/p/2680498.html
Copyright © 2011-2022 走看看