阿里云数据迁移测试连接成功，预检查一直失败

DTS 从ECS自建数据库迁移数据到RDS

问题描述 ： 测试连接成功，预检查一直失败
检测结果：失败
失败原因： 源库的账号或密码有误导致连接失败
失败详情： DTS-002010 Unknow connect db jdbc:mysql://****:3306?characterEncoding=utf8 failure. Original error: For more information please refer to https://help.aliyun.com/document_detail/91420.htm
解决方案： （1）请修改任务配置，填写正确的账号密码后重新进行预检查（2）请联系值班同学协助排查网络问题后重试

在ECS上登录数据库，执行下

mysql> select user,host from mysql.user;
+---------------+-----------+
| user          | host      |
+---------------+-----------+
| account       | %         |
| 用户名     | %         |
| account       | localhost |
| 用户名    | localhost |
| mysql.session | localhost |
| mysql.sys     | localhost |
| root          | localhost |
+---------------+-----------+

这时候就要删除一个localhost

mysql> DELETE FROM `user` WHERE Host='localhost' AND User='用户名';
Query OK, 0 rows affected (0.00 sec)
mysql> select user,host from mysql.user;
+---------------+-----------+
| user          | host      |
+---------------+-----------+
| account       | %         |
| 用户名     | %         |
| account       | localhost |
| mysql.session | localhost |
| mysql.sys     | localhost |
| root          | localhost |
+---------------+-----------+
mysql> flush privileges; 
Query OK, 0 rows affected (0.00 sec)

现在重试预检查就能过了