Group by的用法

Group by的用法

GROUP BY 語句根據一個或多個列對結果集進行分組。在分組的列上我們可以使用 COUNT, SUM, AVG,等函數。

Group by用法：

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

分組后的條件使用 HAVING 來限定，WHERE 是對原始數據進行條件限制。幾個關鍵字的使用順序為 where 、group by 、having、order by ，

單個字段場景：

SELECT

NAME,

SUM (*)

FROM

employee_tbl

WHERE

ID <> 1

GROUP BY

NAME

HAVING

SUM (*) > 5

ORDER BY

SUM (*) DESC;

單個字段場景：

SELECT

CONTENTID,

LOGINNAME,

"MAX" (CREATETIME) AS CREATETIME

FROM

USER_SCORE_RECORD

WHERE

CONTENTID = 640658720

GROUP BY

CONTENTID,

LOGINNAME