replace into和insert into on duplicate key 区别
replace的用法
当不冲突时相当于insert，其余列默认值
当key冲突时，自增列更新，replace冲突列，其余列默认值
Com_replace会加1
Innodb_rows_updated会加1
Insert into …on duplicate key的用法
不冲突时相当于insert，其余列默认值
当与key冲突时，只update相应字段值。
Com_insert会加1
Innodb_rows_inserted会增加1
实验展示
表结构
| create table helei1(id int(10) unsigned NOT NULL AUTO_INCREMENT,name varchar(20) NOT NULL DEFAULT '',age tinyint(3) unsigned NOT NULL default 0,PRIMARY KEY(id),UNIQUE KEY uk_name (name))ENGINE=innodb AUTO_INCREMENT=1 DEFAULT CHARSET=utf8; |
表数据
| root@127.0.0.1 (helei)> select * from helei1;+----+-----------+-----+| id | name | age |+----+-----------+-----+| 1 | 贺磊 | 26 || 2 | 小明 | 28 || 3 | 小红 | 26 |+----+-----------+-----+3 rows in set (0.00 sec) |
replace into用法
| root@127.0.0.1 (helei)> replace into helei1 (name) values('贺磊');Query OK, 2 rows affected (0.00 sec)root@127.0.0.1 (helei)> select * from helei1;+----+-----------+-----+| id | name | age |+----+-----------+-----+| 2 | 小明 | 28 || 3 | 小红 | 26 || 4 | 贺磊 | 0 |+----+-----------+-----+3 rows in set (0.00 sec)root@127.0.0.1 (helei)> replace into helei1 (name) values('爱璇');Query OK, 1 row affected (0.00 sec)root@127.0.0.1 (helei)> select * from helei1;+----+-----------+-----+| id | name | age |+----+-----------+-----+| 2 | 小明 | 28 || 3 | 小红 | 26 || 4 | 贺磊 | 0 || 5 | 爱璇 | 0 |+----+-----------+-----+4 rows in set (0.00 sec) |
replace的用法
当没有key冲突时，replace into 相当于insert，其余列默认值
当key冲突时，自增列更新，replace冲突列，其余列默认值
Insert into …on duplicate key:
| root@127.0.0.1 (helei)> select * from helei1;+----+-----------+-----+| id | name | age |+----+-----------+-----+| 2 | 小明 | 28 || 3 | 小红 | 26 || 4 | 贺磊 | 0 || 5 | 爱璇 | 0 |+----+-----------+-----+4 rows in set (0.00 sec)root@127.0.0.1 (helei)> insert into helei1 (name,age) values('贺磊',0) on duplicate key update age=100;Query OK, 2 rows affected (0.00 sec)root@127.0.0.1 (helei)> select * from helei1;+----+-----------+-----+| id | name | age |+----+-----------+-----+| 2 | 小明 | 28 || 3 | 小红 | 26 || 4 | 贺磊 | 100 || 5 | 爱璇 | 0 |+----+-----------+-----+4 rows in set (0.00 sec)root@127.0.0.1 (helei)> select * from helei1;+----+-----------+-----+| id | name | age |+----+-----------+-----+| 2 | 小明 | 28 || 3 | 小红 | 26 || 4 | 贺磊 | 100 || 5 | 爱璇 | 0 |+----+-----------+-----+4 rows in set (0.00 sec)root@127.0.0.1 (helei)> insert into helei1 (name) values('爱璇') on duplicate key update age=120;Query OK, 2 rows affected (0.01 sec)root@127.0.0.1 (helei)> select * from helei1;+----+-----------+-----+| id | name | age |+----+-----------+-----+| 2 | 小明 | 28 || 3 | 小红 | 26 || 4 | 贺磊 | 100 || 5 | 爱璇 | 120 |+----+-----------+-----+4 rows in set (0.00 sec)root@127.0.0.1 (helei)> insert into helei1 (name) values('不存在') on duplicate key update age=80;Query OK, 1 row affected (0.00 sec)root@127.0.0.1 (helei)> select * from helei1;+----+-----------+-----+| id | name | age |+----+-----------+-----+| 2 | 小明 | 28 || 3 | 小红 | 26 || 4 | 贺磊 | 100 || 5 | 爱璇 | 120 || 8 | 不存在 | 0 |+----+-----------+-----+5 rows in set (0.00 sec) |
