WHERE (IsNumeric(@OrderNumber) <> 1 OR OrderNumber = @OrderNumber) 
             AND (IsNumber(@OrderNumber) = 1 OR OrderNumber LIKE '%' 
                                              + @OrderNumber + '%')

使用CASE语句 更新:之前的语法(正如一些人指出的那样)不起作用。CASE的用法如下:

WHERE OrderNumber LIKE
  CASE WHEN IsNumeric(@OrderNumber) = 1 THEN 
    @OrderNumber 
  ELSE
    '%' + @OrderNumber
  END

或者你可以使用一个IF语句，比如@N。里德指出。

If @LstTransDt is Null
                begin
                    Set @OpenQty=0
                end
            else
                begin
                   Select   @OpenQty=IsNull(Sum(ClosingQty),0)  
                   From  ProductAndDepotWiseMonitoring  
                   Where   Pcd=@PCd And PtpCd=@PTpCd And TransDt=@LstTransDt      
                end 

看看这是否有帮助。

    WHERE OrderNumber LIKE CASE WHEN IsNumeric(@OrderNumber) = 1 THEN @OrderNumber ELSE  '%' + @OrderNumber END

In line case条件将正常工作。

您需要CASE语句

WHERE OrderNumber LIKE
CASE WHEN IsNumeric(@OrderNumber)=1 THEN @OrderNumber ELSE '%' + @OrderNumber END

//使用存储过程按国家和站点筛选用户的示例

CREATE STORED PROCEDURE GetUsers
@CountryId int = null,
@SiteId int = null
AS
BEGIN
SELECT *
        FROM Users
        WHERE
                CountryId  = CASE WHEN ISNUMERIC(@CountryId) = 1 THEN @CountryId ELSE CountryId END AND 
                SiteId     = CASE WHEN ISNUMERIC(@SiteId) = 1 THEN @SiteId ELSE SiteId END END

//从输入的countryId和/或siteId如果存在，否则不过滤