mysql 去除重复记录
有如下sql
SET FOREIGN_KEY_CHECKS=0;
DROP TABLE IF EXISTS `count`;
CREATE TABLE `count` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`a1` int(11) NOT NULL,
`b1` int(11) NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=8 DEFAULT CHARSET=latin1;
INSERT INTO `count` VALUES ('1', '1', '1');
INSERT INTO `count` VALUES ('2', '7', '2');
INSERT INTO `count` VALUES ('3', '2', '1');
INSERT INTO `count` VALUES ('4', '6', '2');
INSERT INTO `count` VALUES ('5', '5', '3');
INSERT INTO `count` VALUES ('6', '2', '0');
INSERT INTO `count` VALUES ('7', '2', '4');
希望获取a1字段值和b1字段值都不重复的记录
返回的正确结果应该是
id a1 b1
'5' '5' '3'
[解决办法]
mysql> select * from `count`;+----+----+----+| id | a1 | b1 |+----+----+----+| 1 | 1 | 1 || 2 | 7 | 2 || 3 | 2 | 1 || 4 | 6 | 2 || 5 | 5 | 3 || 6 | 2 | 0 || 7 | 2 | 4 |+----+----+----+7 rows in set (0.00 sec)mysql> select * from `count` t -> where not exists (select 1 from `count` where (a1=t.a1 or b1=t.b1) and id!=t.id);+----+----+----+| id | a1 | b1 |+----+----+----+| 5 | 5 | 3 |+----+----+----+1 row in set (0.00 sec)mysql>
