我正在为下表中的 PRIMARY KEY
执行 INSERT ... ON DUPLICATE KEY UPDATE
:
DESCRIBE users_interests;
+------------+---------------------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+------------+---------------------------------+------+-----+---------+-------+
| uid | int(11) | NO | PRI | NULL | |
| iid | int(11) | NO | PRI | NULL | |
| preference | enum('like','dislike','ignore') | YES | | NULL | |
+------------+---------------------------------+------+-----+---------+-------+
但是,尽管这些值应该是唯一的,但我发现有 2 行受到了影响。
INSERT INTO users_interests (uid, iid, preference) VALUES (2, 2, 'like')
ON DUPLICATE KEY UPDATE preference='like';
Query OK, 2 rows affected (0.04 sec)
为什么会这样?
编辑
为了比较,请参阅此查询:
UPDATE users_interests SET preference='like' WHERE uid=2 AND iid=2;
Query OK, 1 row affected (0.44 sec)
Rows matched: 1 Changed: 1 Warnings: 0
最佳答案
来自 the manual :
With ON DUPLICATE KEY UPDATE, the affected-rows value per row is 1 if the row is inserted as a new row and 2 if an existing row is updated.
关于mysql - 为什么我的 `INSERT ... ON DUPLICATE KEY UPDATE` 中有 2 行受到影响?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/28154517/