如何在SQL的Where子句中使用If语句？ [英] How to use If Statement in Where Clause in SQL?

问题描述

我需要在sql中的where子句中使用if语句。

I need to use if statement inside where clause in sql.

Select * from Customer
WHERE  (I.IsClose=@ISClose OR @ISClose is NULL)  
AND    
(C.FirstName like '%'+@ClientName+'%' or @ClientName is NULL )    
AND 
 if (@Value=2)
  begin
  (I.RecurringCharge=@Total  or @Total is NULL )    
  end
 else if(@Value=3)
begin
(I.RecurringCharge like '%'+cast(@Total as varchar(50))+'%' or @Total is NULL )  
end

注意：这不是完整的代码。所有内容都在SP中定义。我只需编写理解该问题所需的代码。

Note:This is not the complete code.Everything is defined in SP.I Just written the code that was needed to understand the issue.

提前致谢。

推荐答案

你必须使用 CASE Statement / Expression

Select * from Customer
WHERE  (I.IsClose=@ISClose OR @ISClose is NULL)  
AND    
    (C.FirstName like '%'+@ClientName+'%' or @ClientName is NULL )    
AND 
     CASE @Value
         WHEN 2 THEN (CASE I.RecurringCharge WHEN @Total or @Total is NULL) 
         WHEN 3 THEN (CASE WHEN I.RecurringCharge like 
                               '%'+cast(@Total as varchar(50))+'%' 
                     or @Total is NULL )
     END

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