MySQL避免插入重复记录：唯一性约束

CREATE TABLE `t3` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `c1` int(11) NOT NULL,
  `c2` varchar(20) DEFAULT NULL,
  `c3` int(11) DEFAULT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `c1` (`c1`) USING BTREE
) ENGINE=InnoDB AUTO_INCREMENT=27 DEFAULT CHARSET=latin1;

insert ignore into t3 (c1,c2,c3) values(100,'cc',4),(6,'dd',5);

[SQL] insert ignore into t3 (c1,c2,c3) values(100,'cc',4),(6,'dd',5);
受影响的行: 1
时间: 0.078s

insert into t3 (c1,c2,c3) values(100,'cc',4),(6,'dd',5);

[SQL] insert into t3 (c1,c2,c3) values(100,'cc',4),(6,'dd',5);
[Err] 1062 - Duplicate entry '100' for key 'c1'