SELECT
userid, lastname, firstname , (SELECT COUNT(day) FROM PROFILE WHERE userid = ?) as numday
FROM PROFILE
我想获取每个用户在 PROFILE 表中存在的天数,但我对应该在查询中的问号 (?) 中放置什么值感到困惑。
请帮忙...
最佳答案
试试这个
SELECT
userid, lastname, firstname ,
(SELECT COUNT(day) FROM PROFILE WHERE userid = P.userid) as numday
FROM PROFILE P
更新:使用GROUP BY
SELECT userid, lastname, firstname, COUNT(day) as numday
FROM PROFILE
GROUP BY userid, lastname, firstname
关于mysql - 主查询的值由子查询使用,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/28848692/