mysql创建用户ERROR 1396 (HY000): Operation CREATE USER failed for XXXXXXXX

创建一个已经存在过的用户，即使已经执行过 delete from mysql.user where User='gerrit'

再重新创建也会报错，如下（gerrit账号是已经存在过，并且delete的）：

mysql> CREATE USER 'gerrit'@'localhost' IDENTIFIED BY 'gerrit';
ERROR 1396 (HY000): Operation CREATE USER failed for 'gerrit'@'localhost'

解决方案：

drop user "gerrit"@"localhost";