php - 如果两列都不为空，则更新a列，否则更新b列，否则不执行任何操作

Question

这是我的桌子：叫房间

+---------+---------+-----------+-------------+-------------+-------------+---------+
| room_id | room_no | room_stat | room_name   | player_a_id | player_b_id | turn_of |
+---------+---------+-----------+-------------+-------------+-------------+---------+
|       1 |       1 |         0 | blah        |           0 |           0 |       0 |
|       2 |       5 |         0 | second room |           0 |           0 |       0 |
|       3 |       3 |         0 | 3rd room    |           0 |           0 |       0 |
|       4 |       4 |         0 | 4th room    |           0 |           0 |       0 |
+---------+---------+-----------+-------------+-------------+-------------+---------+

$player_id //contains the id of the player who wants to join

#房间表：

1. 如果 player_a_id !null 和 player_b_id !null 则不更新；如果
2. player_a_id = null 和 player_b_id !null 然后更新房间集
3. player_a_id = $player_id; 如果 player_b_id = null 和 player_a_id !null 则更新房间集 player_b_id = $player_id;

我当前的查询（感谢 JW）（我试图编辑它但无济于事我失败了）。

     UPDATE  room
             SET     player_a_id = IF(player_a_id IS NULL OR player_a_id  = 0 AND player_b_id != :chara_id, :chara_id, player_a_id),
                     player_b_id = IF(player_a_id != :chara_id AND player_b_id IS NOT NULL, :chara_id, player_b_id)
             WHERE   room_id  = :room_id

这很好，但如果两列都为空或 = 0，它会更新两列；我只想更新1。

编辑：

这是示例结果：在 player_id 1 加入 room_id 4 后：

+---------+---------+-----------+-------------+-------------+-------------+---------+
| room_id | room_no | room_stat | room_name   | player_a_id | player_b_id | turn_of |
+---------+---------+-----------+-------------+-------------+-------------+---------+
|       1 |       1 |         0 | blah        |           0 |           0 |       0 |
|       2 |       5 |         0 | second room |           0 |           0 |       0 |
|       3 |       3 |         0 | 3rd room    |           0 |           0 |       0 |
|       4 |       4 |         0 | 4th room    |           1 |           1 |       0 |
+---------+---------+-----------+-------------+-------------+-------------+---------+

因为两列都是空的，所以它更新了我只想更新 1 列的列。

Answer 1

查看您的逻辑，您想将 player_a_id 更新为 $player_id IF player_a_id = 0 并且 player_b_id 不 = 0。

如果player_b_id = 0 并且 player_a_id 不 = 0 ，您想将 player_b_id 更新为 $player_id 。

编辑——如果它们都等于 0，您还想更新 player_a_id。

UPDATE  room
SET     player_a_id = IF(player_a_id=0, :player_id, player_a_id),
    player_b_id = IF(player_a_id!=0 AND player_b_id=0, :player_id, player_b_id)
WHERE   room_id  = :room_id