我有一张有付款要求的桌子。
PaymentId (UNSIGNED INT AI)
ClientId (USINGNED INT)
Amount (FLOAT)
PayTo (DATE)
因为对于PayTo,通常不超过2-3个不同的值(每个客户端),我想创建列表-到今天为止应该支付多少钱。我是在找这样的查询吗?
SELECT PayTo, SUM(IF(PayTo <= PayTo, Amount, 0)) as AmountThisDate
FROM Payments
WHERE ClientId='%d'
GROUP BY PayTo
ORDER BY PayTo DESC
但我百分之百肯定
PayTo <= PayTo
不起作用。
如果是同一列,那么一列一列访问组和表列的正确方法是什么?
发布于 2013-07-23 13:56:39
听起来你想要一个累积的金额。下面是一个使用关联子查询的方法:
SELECT p1.PayDate,
(select sum(p2.amount)
from Payments p2
where p2.ClientId = p.ClientId and
p2.PayDate <= p.PayDate
) as AmountThisDate
FROM Payments p1
WHERE p1.ClientId='%d'
GROUP BY p1.PayDate
ORDER BY p1.PayDate DESC;
通过在payments(ClientId, PayDate, Amount)
上建立索引,性能将得到改善。
发布于 2013-07-23 14:00:56
SELECT PayDate, SUM(IF(PayDate <= current_date(), Amount, 0)) as AmountThisDate
FROM Payments
WHERE ClientId='%d'
GROUP BY PayDate
ORDER BY PayDate DESC
这就是你要找的吗?
https://stackoverflow.com/questions/17812169
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