MySQL COUNT（*）GROUP BY COUNT =？

Question

这是我的查询

SELECT COUNT(*) as total, toys, date FROM T1
 WHERE (date >= '2012-06-26'AND date < '2012-06-30') AND (Avail > '0')
UNION
SELECT COUNT(*) as total, toys, date FROM T2
 WHERE (date >= '2012-06-26'AND date < '2012-06-30') AND (Avail > '0')
UNION
SELECT COUNT(*) as total, toys, date FROM T3
 WHERE (date >= '2012-06-26'AND date < '2012-06-30') AND (Avail > '0')
GROUP BY RoomType
HAVING COUNT( total ) = 4

输出结果

count   Toys            date
3   Bibi        2012-06-26
4   Baba            2012-06-26

如何让MYSQL仅显示count = 4的结果

Answer 1

SELECT * FROM (
    SELECT COUNT(*) as total, toys, date FROM T1
     WHERE (date >= '2012-06-26' AND date < '2012-06-30') AND (Avail > '0')
     GROUP BY RoomType
    UNION
    SELECT COUNT(*) as total, toys, date FROM T2
     WHERE (date >= '2012-06-26' AND date < '2012-06-30') AND (Avail > '0')
     GROUP BY RoomType
    UNION
    SELECT COUNT(*) as total, toys, date FROM T3
     WHERE (date >= '2012-06-26'AND date < '2012-06-30') AND (Avail > '0')
    GROUP BY RoomType) AS src
WHERE total = 4;

请注意，对于正确的数据灌输，您必须将所有列放在GROUP BY子句中或作为聚合函数的参数。 MySQL功能允许您避免此限制，但它可能会导致您意外的结果。

Answer 2

你首先需要组，然后结合结果。

SELECT COUNT(*) as total, toys, date FROM T1
 WHERE (date >= '2012-06-26'AND date < '2012-06-30') AND (Avail > '0')
 GROUP BY RoomType HAVING COUNT( *) = 4
UNION
SELECT COUNT(*) as total, toys, date FROM T2
 WHERE (date >= '2012-06-26'AND date < '2012-06-30') AND (Avail > '0')
 GROUP BY RoomType HAVING COUNT( * ) = 4
UNION
SELECT COUNT(*) as total, toys, date FROM T3
 WHERE (date >= '2012-06-26'AND date < '2012-06-30') AND (Avail > '0')
 GROUP BY RoomType HAVING COUNT( * ) = 4