SQL Count where 子句答案

【问题标题】：SQL Count where clauseSQL Count where 子句
【发布时间】：2010-08-09 14:14:30
【问题描述】：

我有以下 SQL 语句：

 SELECT        [l.LeagueId] AS LeagueId, [l.LeagueName] AS NAME, [lp.PositionId]
 FROM            (Leagues l INNER JOIN
                     Lineups lp ON l.LeagueId = lp.LeagueId)
 WHERE        (lp.PositionId = 1) OR
                     (lp.PositionId = 3) OR
                     (lp.PositionId = 2)

我真正需要的是获取位置计数大于数字的行。比如：

 SELECT        [l.LeagueId] AS LeagueId, [l.LeagueName] AS NAME, [lp.PositionId]
 FROM            (Leagues l INNER JOIN
                     Lineups lp ON l.LeagueId = lp.LeagueId)
 WHERE        Count(lp.PositionId = 1) > 2 OR
                     Count(lp.PositionId = 3) > 6 OR
                     Count(lp.PositionId = 2) > 3

有没有办法在 SQL 中做到这一点？

【问题讨论】：

所以，我在下面使用了 Cade Roux 的解决方案，但是有谁知道为什么，当我将 HAVING 从 OR 语句更改为 AND 语句时，我得到零结果？如果我只使用一个 SUM(CASE..) 语句，我会得到结果，但如果我结合两个有效的语句，我会得到零个结果。

标签： sql join count where-clause having

【解决方案1】：

这个怎么样？

SELECT        [l.LeagueId] AS LeagueId, [l.LeagueName] AS NAME
 FROM            (Leagues l INNER JOIN
                     Lineups lp ON l.LeagueId = lp.LeagueId)
 GROUP BY [l.LeagueId], [l.LeagueName]
 HAVING        SUM(CASE WHEN lp.PositionId = 1 THEN 1 ELSE 0 END) > 2 OR
                     SUM(CASE WHEN lp.PositionId = 3 THEN 1 ELSE 0 END) > 6 OR
                     SUM(CASE WHEN lp.PositionId = 2 THEN 1 ELSE 0 END) > 3

【讨论】：

【解决方案2】：

HAVING 是您要查找的关键字：

SELECT        [l.LeagueId] AS LeagueId, [l.LeagueName] AS NAME, [lp.PositionId]
FROM            (Leagues l INNER JOIN
                     Lineups lp ON l.LeagueId = lp.LeagueId)
GROUP BY lp.PositionId, l.LeagueName
HAVING lp.PositionId = 1 AND COUNT(*) > 2 
       OR lp.PositionId = 2 AND COUNT(*) > 3 
       OR lp.PositionId = 3 AND COUNT(*) > 6

【讨论】：