加入其他表

Question

SELECT saleamount/(SELECT SUM(saleamount) 
                   from user_pr where user_id=49) *100 as totalPercentage 
from user_pr where user_id=49

我也想加入

select users.firstname from users where type=1

如何在一个查询中组合两者

Answer 1

取两个表名，将JOIN置于then和ON之间，并在第二个之后加入条件。

SELECT saleamount/(SELECT SUM(saleamount) 
                   from user_pr where user_id=49) *100 as totalPercentage,
       users.firstname
from user_pr JOIN users ON user_pr.user_id = users.user_id
where user_pr.user_id = 49
 and users.type = 1