update user set passwd=md5("123") where id="1";
insert into user(uName,passwd) values("xiaoqiang",md5("123")) ;
select * from user where uName="lihua" and passwd=md5("123");
update user set passwd=md5("123") where id="1";
insert into user(uName,passwd) values("xiaoqiang",md5("123")) ;
select * from user where uName="lihua" and passwd=md5("123");