replace into和insert into on duplicate key 區別
replace的用法
當不沖突時相當于insert，其余列默認值
當key沖突時，自增列更新，replace沖突列，其余列默認值
Com_replace會加1
Innodb_rows_updated會加1
Insert into …on duplicate key的用法
不沖突時相當于insert，其余列默認值
當與key沖突時，只update相應字段值。
Com_insert會加1
Innodb_rows_inserted會增加1
實驗展示
表結構
| 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; |
表數據
| root@127.0.0.1 (helei)> select * from helei1;+----+-----------+-----+| id | name | age |+----+-----------+-----+| 1 | 賀磊 | 26 || 2 | 小明 | 28 || 3 | 小紅 | 26 |+----+-----------+-----+3 rows in set (0.00 sec) |
replace into用法
| root@127.0.0.1 (helei)> replace into helei1 (name) values('賀磊');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 | 小紅 | 26 || 4 | 賀磊 | 0 |+----+-----------+-----+3 rows in set (0.00 sec)root@127.0.0.1 (helei)> replace into helei1 (name) values('愛璇');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 | 小紅 | 26 || 4 | 賀磊 | 0 || 5 | 愛璇 | 0 |+----+-----------+-----+4 rows in set (0.00 sec) |
replace的用法
當沒有key沖突時，replace into 相當于insert，其余列默認值
當key沖突時，自增列更新，replace沖突列，其余列默認值
Insert into …on duplicate key:
| root@127.0.0.1 (helei)> select * from helei1;+----+-----------+-----+| id | name | age |+----+-----------+-----+| 2 | 小明 | 28 || 3 | 小紅 | 26 || 4 | 賀磊 | 0 || 5 | 愛璇 | 0 |+----+-----------+-----+4 rows in set (0.00 sec)root@127.0.0.1 (helei)> insert into helei1 (name,age) values('賀磊',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 | 小紅 | 26 || 4 | 賀磊 | 100 || 5 | 愛璇 | 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 | 小紅 | 26 || 4 | 賀磊 | 100 || 5 | 愛璇 | 0 |+----+-----------+-----+4 rows in set (0.00 sec)root@127.0.0.1 (helei)> insert into helei1 (name) values('愛璇') 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 | 小紅 | 26 || 4 | 賀磊 | 100 || 5 | 愛璇 | 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 | 小紅 | 26 || 4 | 賀磊 | 100 || 5 | 愛璇 | 120 || 8 | 不存在 | 0 |+----+-----------+-----+5 rows in set (0.00 sec) |
