在linux主机上使用sqlplus进行登录：
[ora12c@gac-oadev-db01 ~]$ sqlplus / as sysdba
SQL*Plus: Release 11.2.0.4.0 Production on Fri Jan 24 11:25:34 2025
Copyright (c) 1982, 2013, Oracle. All rights reserved.
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL> select status from v$insance;
select status from v$insance
*
ERROR at line 1:
ORA-00942: table or view does not exist
查看数据库的状态，状态一般分为nomount,mount,open 三个状态：SQL> select status from v$instance;
STATUS
------------
OPEN
SQL> select sysdate from dual;
SYSDATE
------------------
24-JAN-25
SQL>