insert ignore、insert和replace的区别
测试代码
insert
replace
insert ignore
insert ignore、insert和replace的区别insert | 报错 | 插入 | insert into names(name, age) values(“小明”, 23); |
insert ignore | 忽略 | 插入 | insert ignore into names(name, age) values(“小明”, 24); |
replace | 替换 | 插入 | replace into names(name, age) values(“小明”, 25); |
表要求:有PrimaryKey,或者unique索引
结果:表id都会自增
测试代码创建表
CREATE TABLE names(
id INT(10) PRIMARY KEY AUTO_INCREMENT,
name VARCHAR(255) UNIQUE,
age INT(10)
)
插入数据
mysql> insert into names(name, age) values("小明", 24);
mysql> insert into names(name, age) values("大红", 24);
mysql> insert into names(name, age) values("大壮", 24);
mysql> insert into names(name, age) values("秀英", 24);
mysql> select * from names;
+----+--------+------+
| id | name | age |
+----+--------+------+
| 1 | 小明 | 24 |
| 2 | 大红 | 24 |
| 3 | 大壮 | 24 |
| 4 | 秀英 | 24 |
+----+--------+------+
insert
插入已存在, id会自增,但是插入不成功,会报错
mysql> insert into names(name, age) values("小明", 23);
ERROR 1062 (23000): Duplicate entry '小明' for key 'name'
replace
已存在替换,删除原来的记录,添加新的记录
mysql> replace into names(name, age) values("小明", 23);
Query OK, 2 rows affected (0.00 sec)
mysql> select * from names;
+----+--------+------+
| id | name | age |
+----+--------+------+
| 2 | 大红 | 24 |
| 3 | 大壮 | 24 |
| 4 | 秀英 | 24 |
| 6 | 小明 | 23 |
+----+--------+------+
不存在替换,添加新的记录
mysql> replace into names(name, age) values("大名", 23);
Query OK, 1 row affected (0.00 sec)
mysql> select * from names;
+----+--------+------+
| id | name | age |
+----+--------+------+
| 2 | 大红 | 24 |
| 3 | 大壮 | 24 |
| 4 | 秀英 | 24 |
| 6 | 小明 | 23 |
| 7 | 大名 | 23 |
+----+--------+------+
insert ignore
插入已存在,忽略新插入的记录,id会自增,不会报错
mysql> insert ignore into names(name, age) values("大壮", 25);
Query OK, 0 rows affected, 1 warning (0.00 sec)
插入不存在,添加新的记录
mysql> insert ignore into names(name, age) values("壮壮", 25);
Query OK, 1 row affected (0.01 sec)
mysql> select * from names;
+----+--------+------+
| id | name | age |
+----+--------+------+
| 2 | 大红 | 24 |
| 3 | 大壮 | 24 |
| 4 | 秀英 | 24 |
| 6 | 小明 | 23 |
| 7 | 大名 | 23 |
| 10 | 壮壮 | 25 |
+----+--------+------+
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