-- insert into users(username,`password`,realname)values( ‘ zhangsan ‘ , ‘ 123 ‘ , ‘ 张三 ‘ );
-- select * from users;
-- select id,username from users;
-- select * from users where username= ‘ zhangsan ‘ and `password`= ‘ 123 ‘ ;
-- select * from users where username= ‘ zhangsan ‘ or `password`= ‘ 121 ‘ ;
-- select * from users where username like ‘ %zhang% ‘ ;
-- select * from users where password like ‘ %1% ‘ order by id desc ;