1、远程连接数据库
sqlplus /nolog
conn sys/sys@IP:1521/orainstance as sysdba
2、查看数据库版本
select * from v$version
3、查看当前实例名
select instance from v$thread
4、查看当前数据库名
select name from v$database
5、递归查询
a、查询id等于0的节点下面的所有子节点
select * from myTable start with id='0' connect by prior id = pid
b、查询id等于100的节点上面的所有父节点
select * from myTable start with id='100' connect by id = prior pid