revoke drop on database.* from 'username'@'%';
flush privileges;
revoke drop on database.* from 'username'@'127.0.0.1';
flush privileges;
revoke drop on database.* from 'username'@'localhost';
flush privileges;
取消来自远程服务器的netuser用户对数据库db1的所有表的所有权限
revoke all on database.* from 'username'@'%';
flush privileges;
revoke all on database.* from 'username'@'127.0.0.1';
flush privileges;
revoke all on database.* from 'username'@'localhost';
flush privileges;
drop user 'username'@'%';
drop user 'username'@'127.0.0.1';
drop user 'username'@'localhost';
