![](https://s4.51cto.com/images/blog/201712/13/2b554b2824e3eadc29abb2baf7864043.jpg?x-oss-process=image/watermark,size_16,text_QDUxQ1RP5Y2a5a6i,color_FFFFFF,t_100,g_se,x_10,y_10,shadow_90,type_ZmFuZ3poZW5naGVpdGk=) # 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) # 总结 ----- replace into这种用法,相当于如果发现冲突键,先做一个delete操作,再做一个insert 操作,未指定的列使用默认值,这种情况会导致自增主键产生变化,如果表中存在外键或者业务逻辑上依赖主键,那么会出现异常。因此建议使用Insert into …on duplicate key。由于编写时间也很仓促,文中难免会出现一些错误或者不准确的地方,不妥之处恳请读者批评指正。 喜欢的读者可以点个赞来个关注,您的赞美和关注是对笔者继续发文的最大鼓励与支持!