drop table if exists t1; CREATE TABLE t1 ( id int(11) NOT NULL auto_increment, ggid varchar(32) binary DEFAULT '' NOT NULL, email varchar(64) DEFAULT '' NOT NULL, passwd varchar(32) binary DEFAULT '' NOT NULL, PRIMARY KEY (id), UNIQUE ggid (ggid) ) ENGINE=innodb; insert into t1 (ggid,passwd) values ('test1','xxx'); insert into t1 (ggid,passwd) values ('test2','yyy'); insert into t1 (ggid,passwd) values ('test2','this will fail'); ERROR 23000: Duplicate entry 'test2' for key 'ggid' insert into t1 (ggid,id) values ('this will fail',1); ERROR 23000: Duplicate entry '1' for key 'PRIMARY' select * from t1 where ggid='test1'; id ggid email passwd 1 test1 xxx select * from t1 where passwd='xxx'; id ggid email passwd 1 test1 xxx select * from t1 where id=2; id ggid email passwd 2 test2 yyy replace into t1 (ggid,id) values ('this will work',1); replace into t1 (ggid,passwd) values ('test2','this will work'); update t1 set id=100,ggid='test2' where id=1; ERROR 23000: Duplicate entry 'test2' for key 'ggid' select * from t1; id ggid email passwd 1 this will work 3 test2 this will work select * from t1 where id=1; id ggid email passwd 1 this will work select * from t1 where id=999; id ggid email passwd drop table t1; End of tests