mysql - 从结果集中选择 TOP 1

Question

我想检索使用 Union 连接的查询结果集的前 1 个值

SELECT TOP 1 * FROM
(
    SELECT paused_time as end_time
        FROM production_time
        WHERE created_time = curdate()
    UNION 
    SELECT resumed_time as end_time
        FROM pause_timer
        WHERE created_time = curdate()
    UNION
    SELECT end_time as end_time
        FROM timer_idle
        WHERE created_time = curdate()
) as end_time
ORDER BY end_time DESC 

却得不到预期的结果。

Answer 1

据我所知，MySQL 中没有TOP 关键字。你需要的是Limit:

SELECT * FROM
(
    SELECT paused_time as end_time FROM production_time WHERE created_time = curdate()
    UNION 
    SELECT resumed_time as end_time FROM  pause_timer WHERE created_time = curdate()
    UNION
    SELECT end_time as end_time FROM  timer_idle WHERE created_time = curdate()
) as end_time
ORDER BY end_time DESC 
LIMIT 1