查看实例名：

select name from v$database;

select instance_name from v$instance;

查看实例状态：

SQL> select status from v$instance;
 
STATUS
------------------------
STARTED
 
SQL> alter database mount;
 
数据库已更改。
 
SQL> select status from v$instance;
 
STATUS
------------
MOUNTED
 
SQL> alter database open;
 
数据库已更改。
 
SQL> select status from v$instance;
 
STATUS
------------
OPEN
 
SQL>