MySQL 选择给定日期位于表中存储的日期之间的行

Question

假设我有一些数据，例如:

id  status activity_date
--- ------ -------------
101   R     2014-01-12
101   Mt    2014-04-27 
101   R     2014-05-18
102   R     2014-02-19

请注意，对于 id = 101 的行，我们在 2014-01-12 到 2014-04-26 和 2014-05-18 到当前日期之间有事件。

现在我需要选择 status = 'R' 并且日期是给定日期的最新日期的数据，例如如果我搜索 2014-02-02，我会找到在 2014-01-12 创建的状态行，因为该状态在实体 ID 101 的时间仍然有效。

Answer 1

如果我理解正确的话:

第 1 步:将开始日期和结束日期行转换为列。为此，您必须根据以下条件将表与自身连接起来:

SELECT
    dates_fr.id,
    dates_fr.activity_date AS date_fr,
    MIN(dates_to.activity_date) AS date_to
FROM test AS dates_fr
LEFT JOIN test AS dates_to ON 
    dates_to.id = dates_fr.id AND
    dates_to.status = 'Mt' AND
    dates_to.activity_date > dates_fr.activity_date
WHERE dates_fr.status = 'R'
GROUP BY dates_fr.id, dates_fr.activity_date

+------+------------+------------+
| id   | date_fr    | date_to    |
+------+------------+------------+
|  101 | 2014-01-12 | 2014-04-27 |
|  101 | 2014-05-18 | NULL       |
|  102 | 2014-02-19 | NULL       |
+------+------------+------------+

第 2 步:剩下的就很简单了。将查询包装在另一个查询中并使用适当的 where 子句:

SELECT * FROM (
    SELECT
        dates_fr.id,
        dates_fr.activity_date AS date_fr,
        MIN(dates_to.activity_date) AS date_to
    FROM test AS dates_fr
    LEFT JOIN test AS dates_to ON 
        dates_to.id = dates_fr.id AND
        dates_to.status = 'Mt' AND
        dates_to.activity_date > dates_fr.activity_date
    WHERE dates_fr.status = 'R'
    GROUP BY dates_fr.id, dates_fr.activity_date
) AS temp WHERE '2014-02-02' >= temp.date_fr and ('2014-02-02' < temp.date_to OR temp.date_to IS NULL)

+------+------------+------------+
| id   | date_fr    | date_to    |
+------+------------+------------+
|  101 | 2014-01-12 | 2014-04-27 |
+------+------------+------------+

SQL Fiddle