Group by的用法

Group by的用法

GROUP BY 语句根据一个或多个列对结果集进行分组。在分组的列上我们可以使用 COUNT, SUM, AVG,等函数。

Group by用法：

SELECT column_name, function(column_name)
FROM table_name
WHERE column_name operator value
GROUP BY column_name;

分组后的条件使用 HAVING 来限定，WHERE 是对原始数据进行条件限制。几个关键字的使用顺序为 where 、group by 、having、order by ，

单个字段场景：

SELECT

NAME,

SUM (*)

FROM

employee_tbl

WHERE

ID <> 1

GROUP BY

NAME

HAVING

SUM (*) > 5

ORDER BY

SUM (*) DESC;

单个字段场景：

SELECT

CONTENTID,

LOGINNAME,

"MAX" (CREATETIME) AS CREATETIME

FROM

USER_SCORE_RECORD

WHERE

CONTENTID = 640658720

GROUP BY

CONTENTID,

LOGINNAME