MySQL 刪除重複資料

建表，插入資料，當然如果你不想測試一下，也可以直接用後面的刪除語句

create table if not exists `tb01` (

`id` int unsigned primary key auto_increment,
`name` varchar (10) not null
);insert into `tb01` (`name`)
values
('zhangsan'),
('lisi'),
('wangwu'),
('zhangsan'),
('lisi'),
('wangwu'),
('zhaoliu'),
('wangwu');

mysql>

select
*from tb01;
+----+----------+
| id | name |
+----+----------+|1
| zhangsan ||2
| lisi ||3
| wangwu ||4
| zhangsan ||5
| lisi ||6
| wangwu ||7
| zhaoliu ||8
| wangwu |
+----+----------+
8rows
inset
(0.01 sec)

# 用法：

delete
from
`表名`
where
`主鍵名`
notin
(select
`主鍵名`
from
(select
`主鍵名`
from
`表名`
group
by`重複字段`)`
temp`)
;# 例項：
mysql>
delete
from
`tb01`
where
`id`
notin
(select
`id`
from
(select
`id`
from
`tb01`
group
by`name`)`
temp`)
;query ok,
4rows affected (
0.01 sec)

delete

from
`tb01`
where
`id`
notin
(select
`id`
from
`tb01`
group
by`name`
)

mysql>

delete
from
`tb01`
where
`id`
notin
(select
`id`
from
`tb01`
group
by`name`);
error 1093
(hy000): you can't specify target table 'tb01' for
update
infrom clause

再次查詢，重複的已經刪除

mysql>

select
*from tb01;
+----+----------+
| id | name |
+----+----------+|1
| zhangsan ||2
| lisi ||3
| wangwu ||7
| zhaoliu |
+----+----------+
4rows
inset
(0.00 sec)

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