Question

我有3个表，即客户，信用和付款。我希望得到客户在@StartDate和@EndDate之间做出的所有付款和信用。这是我的查询：

SELECT         Client.Name, Payment.PaymentAmount, Credit.CreditAmount
FROM            Client  

LEFT JOIN Payment 
ON Client.ClientID = Payment.ClientID 
LEFT  JOIN Credit
ON Client.ClientID = Credit.ClientID 

WHERE       (Payment.Date BETWEEN @StartDate AND @EndDate) AND (Client.Date BETWEEN @StartDate AND @EndDate)
ORDER BY Client.CName

我想显示所有信用额度，即使付款没有用信用卡支付，而支票也是NULL，反之亦然。但我无法得到它，因为它只显示该客户在该日期的信用和付款。

我尝试过OR而不是AND（使用＆＃39; WHERE＆＃39;）但它也不起作用。

Answer 1

您可以通过将条件移至on子句来获得所需内容：

SELECT c.Name, p.PaymentAmount, cr.CreditAmount
FROM Client c LEFT JOIN
     Payment p
     ON c.ClientID = p.ClientID AND p.Date BETWEEN @StartDate AND @EndDate LEFT JOIN
     Credit cr
     ON c.ClientID = cr.ClientID AND cr.Date BETWEEN @StartDate AND @EndDate
ORDER BY c.CName;

但是，我不确定这是你真正想要的东西，因为它在支付和信用之间做了一个笛卡尔产品，在这段时间内不止一个。

这可能更接近你真正想要的东西：

SELECT c.Name, p.PaymentAmount, NULL as CreditAmount
FROM Client c LEFT JOIN
     Payment p
     ON c.client_id = p.ClientId AND p.Date BETWEEN @StartDate AND @EndDate
UNION ALL
SELECT c.Name, NULL, c.CreditAmount
FROM Client c LEFT JOIN
     Credit cr
     ON c.ClientID = cr.ClientID AND cr.Date BETWEEN @StartDate AND @EndDate
ORDER BY Name;

左加入多个条件

1 个答案: