Question

使用SQL Server，我可以使用别名来命令正常的SELECT查询：

SELECT   
   u.FirstName + ' ' + u.LastName as PhysicianName, COUNT(r.Id) as ReferralsCount
FROM     
   Referrals r 
INNER JOIN
   Users u ON r.PhysicianId = u.Id
GROUP BY 
   r.PhysicianId, u.FirstName, u.LastName
ORDER BY 
   PhysicianName

但是，尝试使用动态ORDER BY执行相同的操作：

SELECT   
   u.FirstName + ' ' + u.LastName as PhysicianName, COUNT(r.Id) as ReferralsCount
FROM     
   Referrals r 
INNER JOIN
   Users u ON r.PhysicianId = u.Id
GROUP 
   BY r.PhysicianId, u.FirstName, u.LastName
ORDER BY 
    CASE WHEN @orderby = 'PhysicianName' THEN PhysicianName END,
    CASE WHEN @orderby = 'ReferralsCount' THEN ReferralsCount END

产生以下错误：

Msg 207，Level 16，State 1，Line 10
  列名称“PhysicianName”无效。
  Msg 207，Level 16，State 1，Line 11   列名称“ReferralsCount”无效。

Answer 1

SELECT中定义的列别名只能在ORDER BY中自行使用。不在表达中。

您可以按如下方式调整原始尝试。

;WITH T
     AS (SELECT u.FirstName + ' ' + u.LastName AS PhysicianName,
                COUNT(r.Id)                    AS ReferralsCount
         FROM   Referrals r
                INNER JOIN Users u
                  ON r.PhysicianId = u.Id
         GROUP  BY r.PhysicianId,
                   u.FirstName,
                   u.LastName)
SELECT *
FROM   T
ORDER  BY CASE
            WHEN @orderby = 'PhysicianName' THEN PhysicianName
          END,
          CASE
            WHEN @orderby = 'ReferralsCount' THEN ReferralsCount
          END

SQL动态ORDER BY使用别名

1 个答案: