如何在where闭包内使用IF语句 [英] How to use IF statement inside a where closure

问题描述

这是我的代码：

如何在封闭的地方使用IF语句，请帮我重新安排这些代码

  WHERE  
  IF  IsNumeric（ @ OrderNumber ）=  1  
 OrderNumber =  @ OrderNumber  
  ELSE  
 BillId =  @ OrderNumber  
 
 < b>我尝试过： 
 
  WHERE  
  IF  IsNumeric（ @ OrderNumber ）=  1  
 OrderNumber =  @ OrderNumber  
  ELSE  
 BillId =  @ OrderNumber  

解决方案

使用案例：

  WHERE    -   基于值 
  CASE  IsNumeric（ @ OrderNumber ）
  WHEN   1  那么 OrderNumber =  @ OrderNumber  
  ELSE  BillId =  @ OrderNumber  
  END  

  WHERE    -   基于布尔值 
  CASE  
  WHEN  IsNumeric（ @ OrderNumber ）=  1   T HEN  OrderNumber =  @ OrderNumber  
  ELSE  BillId =  @ OrderNumber  
  END  

希望有所帮助^ _ ^

Andy





更新：实际上，正如所指出的，这个不行。案例只能返回一个值，不能用作逻辑条件。



在这种情况下可以这样使用：

  WHERE    -    boolean基于 
  CASE  
  WHEN  IsNumeric（ @ OrderNumber ）=  1  那么 OrderNumber 
  ELSE  BillId 
  END  =  @ OrderNumber  

或者，同样有效的是使用OR子句：

  WHERE    -     
（IsNumeric（ @ OrderNumber ）=  1   AND  OrderNumber =  @ OrderNumber ）
 或 
（IsNumeric（ @ OrderNumber ）=  0   AND  BillId =  @ OrderNumber ）

This is my code:
How to use IF statement inside a where closure,Plese help me for re-arrange these code

WHERE
	IF IsNumeric(@OrderNumber) = 1
		OrderNumber = @OrderNumber
	ELSE
	        BillId= @OrderNumber

What I have tried:

WHERE
   IF IsNumeric(@OrderNumber) = 1
		OrderNumber = @OrderNumber
	ELSE
	        BillId= @OrderNumber

解决方案

Use CASE:

WHERE --Value based
    CASE IsNumeric(@OrderNumber)
    WHEN 1 THEN OrderNumber = @OrderNumber
    ELSE BillId= @OrderNumber
    END

WHERE --boolean based
    CASE 
    WHEN IsNumeric(@OrderNumber) = 1 THEN OrderNumber = @OrderNumber
    ELSE BillId= @OrderNumber
    END

Hope that helps ^_^
Andy


UPDATE: Actually, as pointed out, this won't work. The case can only return a value, not be used as a logical condition.

It can be used in this case as so:

WHERE --boolean based
    CASE 
    WHEN IsNumeric(@OrderNumber) = 1 THEN OrderNumber
    ELSE BillId
    END = @OrderNumber

or, just as valid would be to use an OR clause:

WHERE --
    ( IsNumeric(@OrderNumber) = 1 AND OrderNumber = @OrderNumber)
    OR
    ( IsNumeric(@OrderNumber) = 0 AND BillId= @OrderNumber)

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