文档解释
ORA-12318: database (link name string) is already mounted
Cause: You are attempting to mount a secondary database that has already been mounted by your instance.
Action: to mount it. To establish access, use the ALTER DATABASE OPEN command to open the database.
ORA-12318 错误表示该数据库已经被挂载。
官方解释
常见案例
正常处理方法及步骤
1.使用ALTER DATABASE DISMOUNT命令取消挂载数据库；
2.检查当前数据库是否在挂载状态，使用SQL> SELECT * FROM V$DATABASE;命令；
3.如果当前数据库不在挂载状态，可以使用ALTER DATABASE MOUNT命令挂载数据库。
