查看：
SELECT DISTINCT CONCAT('User: ''',user,'''@''',host,''';') AS query FROM mysql.user;
删除：
drop user 'username'@'host';
mysql> SELECT DISTINCT CONCAT('User: ''',user,'''@''',host,''';') AS query FROM mysql.user;
+-----------------------------------+
| query |
+-----------------------------------+
| User: 'root'@'127.0.0.1'; |
| User: 'slaveuser'@'192.168.15.%'; |
| User: 'root'@'::1'; |
| User: 'username'@'host'; |
| User: ''@'localhost'; |
| User: 'root'@'localhost'; |
| User: ''@'vm-linux-t'; |
| User: 'root'@'vm-linux-t'; |
+-----------------------------------+
8 rows in set (0.00 sec)
mysql> drop user 'username'@'host';
Query OK, 0 rows affected (0.00 sec)
mysql> SELECT DISTINCT CONCAT('User: ''',user,'''@''',host,''';') AS query FROM mysql.user;
+-----------------------------------+
| query |
+-----------------------------------+
| User: 'root'@'127.0.0.1'; |
| User: 'slaveuser'@'192.168.15.%'; |
| User: 'root'@'::1'; |
| User: ''@'localhost'; |
| User: 'root'@'localhost'; |
| User: ''@'vm-linux-t'; |
| User: 'root'@'vm-linux-t'; |
+-----------------------------------+
7 rows in set (0.00 sec)
mysql>