Question

可能重复：
sql server use computed column

有没有办法做到这一点：

select Name, 
    (SELECT Max(reference) 
        from Rematch 
        WHERE Gender='M' and convert(varchar,getdate,103) = '08/10/2012'
    ) As MaxReferenceMale, 
    (SELECT Max(reference) 
        from Rematch 
        WHERE Gender='F' and convert(varchar,getdate,103) = '08/10/2012'
    ) As MaxReferenceFemale
WHERE (Gender='M' and Reference > MaxReferenceMale) Or 
    (Gender='F' and Reference > MaxReferenceFemale)

我意识到可能有更好的方法来编写查询。是否可以在WHERE子句中引用MaxReferenceFemale和MaxReferenceMale？

Answer 1

坚持

SELECT * FROM (...) WHERE ...

围绕您的查询。一旦WHERE子句位于外部SELECT的内部，就可以使用别名列。

Answer 2

如果要在WHERE子句中引用它们，则需要子查询：

SELECT *
FROM
(
   select Name,  Gender, Reference 
      (SELECT Max(reference) 
        from Rematch 
        WHERE Gender='M' and convert(varchar,getdate,103) = '08/10/2012') As MaxReferenceMale, 
      (SELECT Max(reference) 
        from Rematch WHERE Gender='F' and convert(varchar,getdate,103) = '08/10/2012') As MaxReferenceFemale
) x
WHERE (Gender='M' and Reference > MaxReferenceMale) 
    Or (Gender='F' and Reference > MaxReferenceFemale)

查看原始查询，看起来您在查询中缺少FROM子句，因此使用子查询语法将类似于此：

select x.name, x.MaxReferenceMale, x.MaxReferenceFemale
from rematch r
left join
(
    select Name, 
        (SELECT Max(reference) 
            from Rematch 
            WHERE Gender='M' and convert(varchar,getdate,103) = '08/10/2012'
        ) As MaxReferenceMale, 
        (SELECT Max(reference) 
            from Rematch 
            WHERE Gender='F' and convert(varchar,getdate,103) = '08/10/2012'
        ) As MaxReferenceFemale
    from rematch
) x
    on r.name = x.name
WHERE (r.Gender='M' and r.Reference > x.MaxReferenceMale) Or 
    (r.Gender='F' r.and Reference > x.MaxReferenceFemale)

SQL - WHERE子句中的派生字段

2 个答案: