日期:2014-05-17  浏览次数:20394 次

链表求和问题
2个表
a:
id,user_name,regtime
b:
id,pay,user_name
现在表a的user_name和b是关联的
想查出表a的所有记录,再加上个字段
是在表b里的支付次数,我知道sum函数,但是忘了怎么关联了,哪位大侠指导一下!

------解决方案--------------------
from a left join b on a.user_name=b.user_name


------解决方案--------------------
SQL code

select 
    a.id,
    a.user_name,
    a.regtime,
    sum(b.Pay)
from a 
left join b on a.user_name=b.user_name
group by a.id,a.user_name,a.regtime

------解决方案--------------------
SQL code
select a.id,a.user_name,a.regtime,sum(b.pay)
from a
left join b 
on a.user_name=b.user_name
group by a.id,a.user_name,a.regtime

------解决方案--------------------
SQL code
select a.id,a.user_name,a.regtime,sum(pay)
from a
left join b 
on a.user_name=b.user_name
group by a.id,a.user_name,a.regtime