查询用户

select User,Host,authentication_string from mysql.user;

 授权

grant select privileges on aaa.bbb to "abc"@"%" identified by "123456"; #创建一个只有对aaa库下的bbb表查询权限、可以在任何ip登陆的abc用户
grant all privileges on *.* to "user"@"%" identified by "123456";  #同理，创建所有权限（除grant）的用户