来自主查询的值被子查询使用

Question

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 中的天数 table 但我不知道应该在查询中的问号 (?) 中放置什么值。

请帮忙...

Answer 1

试试这个未经测试的查询：

SELECT 
   userid, lastname, firstname , numday
FROM PROFILE as p join (SELECT COUNT(day) as numday, userid FROM DTR group by userid ) as q on p.userid = q.userid

Answer 2

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

来自主查询的值被子查询使用

value from main query is used by the subquery

mysql

sql

jdbc