日期:2014-05-16  浏览次数:20864 次

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)

id uid gid
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
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)

id uid gid
1 11 502
2 107 502