1.本地登录
sqlplus / as sysdba
2.账号密码登录
sqlplus user/passwd as sysdba
3.选择实例登录
sqlplus user/passwd@实例名
4.连接远程数据库实例 sqlplus user/passwd@IP:端口/实例名
sqlplus user/passwd@192.168.1.2:1521/orcl
5.远程登录dba实例 sqlplus user/passwd@IP:端口/实例名 as sysdba
sqlplus user/passwd@192.168.1.2:1521/orcl as sysdba