WHERE子句中的SQL派生字段

可能重复：

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)

我意识到也许有更好的方法来写这个问题。可以在WHERE子句中引用MaxReferenceFemale和MaxReferenceMale吗？

粘贴a

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

围绕你的问题。一旦WHERE子句位于外部SELECT的内部，就可以在其中使用别名列。

粘贴一个

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

---

围绕你的问题。一旦WHERE子句位于外部SELECT子句的内部，就可以在其中使用别名列。

如果要在

WHERE

子句中引用别名列，则需要一个子查询：

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，查询中似乎缺少一个

FROM

子句，因此子查询的语法类似于此：

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)

---

如果要在

WHERE

子句中引用它们，则需要一个子查询：

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，查询中似乎缺少一个

FROM

子句，因此子查询的语法类似于此：

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)

---

也称为子查询或派生表。实际上，您需要给子查询加上别名，例如，

SELECT*FROM（…）子查询别名，其中…

您不需要给外部查询加上别名，除非您将其连接到某个对象，但最好将所有内容都加上别名。@monitorjbl-取决于DBMS。在SQL Server中，它是必需的。@Martin Smith-啊，我不知道，我以前从未使用过SQL Server。@monitorjbl，感谢您提供了简单有效的解决方案。也称为子查询或派生表。实际上，您需要给子查询加上别名，例如，

SELECT*FROM（…）子查询别名，其中…

您不需要给外部查询加上别名，除非您将其连接到某个对象，但最好将所有内容都加上别名。@monitorjbl-取决于DBMS。在SQL Server中，这是必须的。@Martin Smith-啊，我不知道，我以前从未使用过SQL Server。@monitorjbl，感谢您提供了简单而有效的解决方案。@Tim Schmelter，SQL Server。很抱歉遗漏了这一点。@Tim Schmelter，SQL Server。很抱歉错过了这个。