在 SQL Server 的 WHERE 子句中使用带有 CASE 语句的“IN”谓词

Question

这是一个运行良好的 SQL 查询：

DECLARE @IncludePTO AS CHAR
SET @IncludePTO = 'Y'

SELECT     
   HQCO.HQCo, HQCO.Name, PREH.PRDept, PREH.Craft, HRRM.PositionCode, PRTH.Employee, 
   PREH.LastName, PREH.FirstName, SUM(PRTH.Hours) AS Hrs
FROM PREH 
INNER JOIN HRRM ON PREH.PRCo = HRRM.HRCo AND PREH.Employee = HRRM.HRRef 
INNER JOIN PRTH ON PREH.PRCo = PRTH.PRCo AND PREH.Employee = PRTH.Employee 
INNER JOIN HQCO ON PRTH.PRCo = HQCO.HQCo
WHERE     
    (dbo.PRTH.PREndDate BETWEEN '1/1/2012 00:00:00' AND '1/1/2013 00:00:00')
    AND (PRGroup = 2)
    AND dbo.PRTH.EarnCode IN (1,3,8)
GROUP BY 
    HQCO.HQCo, HQCO.Name, PREH.PRDept, PREH.Craft, 
    HRRM.PositionCode, PRTH.Employee, PREH.LastName, PREH.FirstName

但是，我正在尝试在 WHERE 子句中使用“IN”谓词和 CASE WHEN。看看下面修改后的查询：

DECLARE @IncludePTO AS CHAR
SET @IncludePTO = 'Y'

SELECT     
   HQCO.HQCo, HQCO.Name, PREH.PRDept, PREH.Craft, HRRM.PositionCode, PRTH.Employee, 
   PREH.LastName, PREH.FirstName, SUM(PRTH.Hours) AS Hrs
FROM PREH 
INNER JOIN HRRM ON PREH.PRCo = HRRM.HRCo AND PREH.Employee = HRRM.HRRef 
INNER JOIN PRTH ON PREH.PRCo = PRTH.PRCo AND PREH.Employee = PRTH.Employee 
INNER JOIN HQCO ON PRTH.PRCo = HQCO.HQCo
WHERE     
    (dbo.PRTH.PREndDate BETWEEN '1/1/2012 00:00:00' AND '1/1/2013 00:00:00')
    AND (PRTH.PRGroup = 2)
    AND 
       CASE WHEN @IncludePTO = 'Y' THEN dbo.PRTH.EarnCode IN (1,2,3,8,100,110,120,115)
            ELSE dbo.PRTH.EarnCode IN (1,2,3,8)
       END
GROUP BY 
    HQCO.HQCo, HQCO.Name, PREH.PRDept, PREH.Craft, HRRM.PositionCode, PRTH.Employee, 
    PREH.LastName, PREH.FirstName

它似乎不起作用并不断给我一个语法错误：

消息 156，第 15 级，状态 1，第 15 行
关键字“IN”附近的语法不正确。

在指出我缺少什么方面有任何帮助或指导吗？非常感谢任何帮助/提示。非常感谢，

普拉纳夫

Answer 1

你是对的。不允许使用该语法。你可以试试：

((@IncludePTO = 'Y' and dbo.PRTH.EarnCode IN (1,2,3,8,100,110,120,115)) or
 (@IncludePTO <> 'Y' and dbo.PRTH.EarnCode IN (1,2,3,8))
)

这可以简化为：

(bo.PRTH.EarnCode IN (1,2,3,8) or (@IncludePTO <> 'Y' and dbo.PRTH.EarnCode IN (100,110,120,115))
)

这假定@IncludePTO 永远不会为NULL。如果是这样，那么这将是测试的一部分。

如果你真的想要where子句中的case语句，你可以这样做：

(CASE WHEN @IncludePTO = 'Y' and dbo.PRTH.EarnCode IN (1,2,3,8,100,110,120,115)
      then 'true'
      when @IncludePTO <> 'Y' and dbo.PRTH.EarnCode IN (1,2,3,8)
      then 'true'
      else 'false'
 end) = 'true'