Question

我正在查询表1中基于子查询的日期列。 where子句中的子查询1从外键引用表获取描述，子查询2通过其他条件获取数据。

所以我的问题是，我有什么选择让这个查询变得更好？

SELECT count(*) AS non_saturday
FROM t_booking
WHERE p_id IN (
        SELECT p_id
        FROM p_detail
        WHERE p_name IN ('A','B')
        )
    AND date_format(p_date, '%Y%m%d') IN (
        SELECT DISTINCT CONCAT (
                gregorian_ccyy
                ,gregorian_month
                ,gregorian_day
                )
        FROM m_gregorian_calendar1 c
        WHERE c.day_of_the_week = (
                SELECT day_id
                FROM m_gregorian_day
                WHERE day_name = 'SATURDAY'
                )
            AND c.gregorian_ccyy = '2012'
            AND c.gregorian_month = '10'
        )

Answer 1

这可能不是你问题的直接答案，但是如果“星期六”你的意思是直接的星期六（而不是某个日历与日期和星期几之间有不同的映射），在我看来你可以简单地运行

SELECT count(*) AS non_saturday
    FROM t_booking
    JOIN p_detail ON (t_booking.p_id = p_detail.p_id AND p_name IN ('A','B'))
    WHERE
        DAYOFWEEK(p_date) = 7
        AND MONTH(p_date) = 10
        AND YEAR (p_date) = 2012

或更好地在p_date字段上使用索引，

    WHERE p_date BETWEEN "2012-10-01" AND "2012-10-31"

（但在日期字段中使用BETWEEN时，请同时选中this answer）。

一堆子查询的可能替代方案

1 个答案: