MYSQL中剔除重复记录的方法

MYSQL中删除重复记录的方法

在实际应用中，很可能会碰到一些需要删除某些字段的重复记录，我现在把我能想到的写下来，望高手们补充。

1、
具体实现如下：

Table???????? Create Table???????????????????????????????????????????
————? ——————–
users_groups? CREATE TABLE `users_groups` (??????????????????????????
??????????????? `id` int(10) unsigned NOT NULL AUTO_INCREMENT,???????
??????????????? `uid` int(11) NOT NULL,??????????????????????????????
??????????????? `gid` int(11) NOT NULL,??????????????????????????????
??????????????? PRIMARY KEY (`id`)???????????????????????????????????
????????????? ) ENGINE=InnoDB AUTO_INCREMENT=15 DEFAULT CHARSET=utf8?



users_groups.txt内容：


1,11,502
2,107,502
3,100,503
4,110,501
5,112,501
6,104,502
7,100,502
8,100,501
9,102,501
10,104,502
11,100,502
12,100,501
13,102,501
14,110,501


mysql> load data infile ‘c:\\users_groups.txt’ into table users_groups fields


terminated by ‘,’ lines terminated by ‘\n’;

Query OK, 14 rows affected (0.05 sec)

Records: 14? Deleted: 0? Skipped: 0? Warnings: 0

mysql> select * from users_groups;

query result(14 records)

14 rows in set (0.00 sec)


根据一位兄弟的建议修改。


mysql> create temporary table tmp_wrap select * from users_groups group by uid having count(1) >= 1;

Query OK,?7 rows affected (0.11 sec)

Records:?7? Duplicates: 0? Warnings: 0

mysql> truncate table users_groups;

Query OK, 14 rows affected (0.03 sec)

mysql> insert into users_groups select * from tmp_wrap;

Query OK,?7 rows affected (0.03 sec)

Records:?7? Duplicates: 0? Warnings: 0

mysql> select * from users_groups;

query result(7 records)