MySQL COUNT(*) GROUP BY HAVING 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 只显示 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，为了进行正确的数据分组，您必须在 GROUP BY 子句中或将所有列作为聚合函数的参数。 MySQL 的特性可以让你避免这个限制，但它可能会导致你意想不到的结果。