使用if语句进行SQL检查

Question

关于SQL的快速问题如何进行检查，如：

Alter Table Invoices WITH NOCHECK
ADD CHECK 

现在，这是我要添加支票的部分，以便column PaymentDate can be null if another column Payment Total is equal to 0和also that PaymentDate is not null if Payment Total is greater than 0。

Answer 1

这是一种方法：

Alter Table Invoices WITH NOCHECK
ADD CHECK (   (PaymentTotal > 0 AND PaymentDate IS NOT NULL) 
           OR (PaymentTotal = 0 ) )