???????????в????????????????????и?????????????????????????????????
??????????????
??????????????????????select????????????????????????????????????????????insert???????????Ч?????????????????select??insert???????????????????????insert??????????????????????????????????
??????????????????
???????????????????????????????????????unique????????????????insert ignore???
???????磺????????????mysql5??
?????????????????洢?????
create table user_info
(
uid mediumint(10) unsigned NOT NULL auto_increment primary key??
last_name char(20) not null??
first_name char(20) not null??
unique ( last_name?? first_name)
);
?????????????
????insert ignore into user_info (last_name??first_name) values ('x'??'y');
????//???????????????????????last_name='x'??first_name='y'???????????????????л??????????????