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.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
Invalid column name ‘PhysicianName’.
Msg 207,Line 11
Invalid column name ‘ReferralsCount’.
解决方法
SELECT中定义的列别名只能在ORDER BY中单独使用.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.LastName)
SELECT *
FROM T
ORDER BY CASE
WHEN @orderby = 'PhysicianName' THEN PhysicianName
END,CASE
WHEN @orderby = 'ReferralsCount' THEN ReferralsCount
END
