MySQL 多次左外连接同一个表？

Question

所以我遇到了一个MySQL的困境，看似比较简单，其实不然。

我有两个表:一个包含要显示的唯一 ID 列表，另一个表在时间戳旁边列出了 ID。

======   ============================
| ID |   | ID |      Timestamp      |
======   ============================
| 1  |   | 1  | 2015-10-10 00:00:00 |
| 2  |   | 1  | 2015-10-10 00:10:00 |
| .. |   | 2  | 2015-10-10 00:00:00 |
======   ============================

如果相关 id 在表 B 中有记录，我需要显示一个 bool 值 在两个日期时间 和它一直处于事件状态的最后一个日期 .

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我试过类似的东西:

SELECT 
    a.`ID`, 
    MAX(b1.`Timestamp`) IS NOT NULL as 'Active',
    MAX(b2.`Timestamp`) AS 'LastActive'
FROM `Table-A` a
LEFT OUTER JOIN `Table-B` b1
    ON a.ID = b1.ID
    AND b1.`Timestamp` BETWEEN @startTime AND @endTime
LEFT OUTER JOIN `Table-B` b2
    ON a.ID = b2.ID
GROUP BY a.ID
;

目前不确定原因:但查询似乎无限运行并且得不到任何结果。任何人都可以建议正确的方法来获得我的查询所需的结果吗？

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编辑:

这是上述查询的 EXPLAIN SELECT。

Answer 1

使用这个

SELECT 
    a.*, 
    IF(b1.cnt IS NULL, FALSE, TRUE) AS is_found, 
    IFNULL(b2.dt, '-') AS max_dt 
FROM table1 a 
    LEFT OUTER JOIN (
        SELECT 
            id, 
            COUNT(*) AS cnt 
        FROM table2 
        WHERE 
            `timestamp` BETWEEN '2015-01-01' AND '2015-12-31' 
        GROUP BY 1) b1 
    ON a.id=b1.id 
    LEFT OUTER JOIN (
        SELECT id, 
            MAX(TIMESTAMP) AS dt 
        FROM table2 
        GROUP BY 1) b2 
    ON a.id=b2.id