sql - 如何在 WHERE 子句中引用别名？

Question

这是我的声明:

SELECT 
  C.Account, 
  (RTRIM(N.FIRST) + ' ' + RTRIM(LTRIM(N.MIDDLE)) + ' ' + RTRIM(LTRIM(N.LAST)) + ' ' + LTRIM(N.SUFFIX)) AS OwnerName,
  DateAdd(dd, -1, C.ExpirationDate) as RealExpirationDate, 
  C.Description, 
  C.Type
FROM CARD as C
  INNER JOIN NAME as N ON C.Account = N.Account
WHERE (RealExpirationDate BETWEEN @StartDate AND @EndDate)
  AND C.Type IN(10,15,17,25)

我不断收到错误消息，指出 RealExpirationDate 是无效的列名称。我如何引用该别名？

Answer 1

你不能在上面的代码中，记住WHERE发生在SELECT之前，所以你必须使用:

WHERE DateAdd(dd, -1, C.ExpirationDate) BETWEEN @StartDate AND @EndDate

给类似的东西起别名的最常见方法是一些内部 View /查询，如下所示:

SELECT
  n.FooBar,  --here we can use FooBar
  t.BarFoo
FROM
  MyTable t
INNER JOIN
(
 SELECT
   myTestCase as FooBar
 From MyTable2
) n