SQL 子句中的条件 WHERE

Question

我需要根据参数的值设置WHERE条件。

这是WHERE子句：

WHERE 
   T1.SalesPerson IN (
      SELECT VendorName FROM dbo.TB_grpVendor WHERE GroupName = @Group
   ) AND 
   (
     T0.DocDate >= @DateBegin AND T0.DocDate <= @DateEnd OR 
     T0.DocDate >= @DateBegin2 AND T0.DocDate <= @DateEnd2
   ) AND 
   T0.CANCELED <> 'Y'

变量@Group是一个参数。 如果它等于"ALL" ，我需要忽略WHERE的第一部分。 我怎样才能做到这一点？

Answer 1

您可以添加OR ：

where (@Group = 'ALL' OR
       EXISTS (SELECT 1 
               FROM dbo.TB_grpVendor 
               WHERE VendorName = T1.SalesPerson AND GroupName = @Group
               )
       ) AND
       . . . 

Answer 2

您可以使用逻辑or运算符实现此功能：

WHERE (@Group = 'ALL' OR 
       T1.SalesPerson IN (SELECT VendorName FROM dbo.TB_grpVendor WHERE GroupName = @Group)) AND 
      (T0.DocDate >= @DateBegin AND T0.DocDate <= @DateEnd OR  
       T0.DocDate >= @DateBegin2 AND T0.DocDate <= @DateEnd2 ) AND 
      (T0.CANCELED <> 'Y')

Answer 3

似乎用 JOIN 处理会更好

INNER JOIN dbo.TB_grpVendor GV on T1.SalesPerson = GV.VendorName
    AND @GroupName IN ('All', GV.GroupName)
WHERE
(
    T0.DocDate >= @DateBegin AND T0.DocDate <= @DateEnd OR 
    T0.DocDate >= @DateBegin2 AND T0.DocDate <= @DateEnd2
)
AND T0.CANCELED <> 'Y'