SQL Server 2008存储过程中的复合条件

Question

如果存储过程允许处理复合条件,请告诉我:

if(
    ( (select Count(*) from dbo.Membership where EmailID=@emailID) >0) 
                                  || 
    ((select Count(*) from dbo.Allocation where ResourceEmail=@emailID)>0))
)

Answer 1

用OR而不是||

如果只检查是否存在更优化,我会使用EXISTS而不是COUNT,因为它会在它第一次存在时停止,而不是全部计算...

IF EXISTS(SELECT 1 FROM dbo.Membership WHERE EmailId = @emailID)
    OR EXISTS(SELECT 1 FROM dbo.Allocation where ResourceEmail=@emailID)
    BEGIN
       -- emailID exists in one of the 2 tables
    END