SELECT username,SUM(ycnum) AS yznum,SUM(zfnum) AS zfnum
FROM
(select * from tempactive where exists
(select * from topic1activeuser where username=tempactive.username)
UNION
select * from topic
mysql 两个查询结果 并 运算
select column1 as one from a where id=1；
select column2 as two from b where id=1；
求 one two 运算
加法
select ( (select column1 as one from a where
