Question

我有一组需要播放的曲目，数据库中有70个轨道，我的脚本需要生成一个新ID才能开始下一个轨道。

当前查询:( $ row ['v_artist']是当前正在播放的艺术家）

SELECT *
FROM t_tracks
WHERE v_artist NOT LIKE '%".$row['v_artist']."%'
ORDER BY RAND()
LIMIT 1;

现在我想为rand（）添加一个子查询，以便它选择一个随机id，但不是从前50个（不是IN？）

子查询：

SELECT *
FROM `t_playlist`
ORDER BY pl_last_played DESC
LIMIT 50, 1

如何从t_tracks中获取t_playlist查询中不存在的随机ID？

Answer 1

从概念上讲，我认为你想要这个：

SELECT *
FROM t_tracks
WHERE v_artist NOT LIKE '%".$row['v_artist']."%' AND
      track_id NOT IN (SELECT track_id FROM t_playlist ORDER BY pl_last_played DESC LIMIT 50)
ORDER BY RAND()
LIMIT 1;

但是，MySQL在某些子查询中不允许LIMIT，因此请改用LEFT JOIN：

SELECT t.*
FROM t_tracks t LEFT JOIN
     (SELECT track_id
      FROM t_playlist
      ORDER BY pl_last_played DESC
      LIMIT 50
     ) p
     ON t.track_id = p.track_id
WHERE t.v_artist NOT LIKE '%".$row['v_artist']."%' AND
      p.track_id IS NULL
ORDER BY RAND()
LIMIT 1;

MySQL Rand（）不在子查询中？

1 个答案: