查看现在在那个数据库中

select * from v$database; -- 查看在那个数据库中。


v$xxx 开头的都是dba 使用的，普通的用户要查看
必须使用：grant select any dictionary to user 赋予查询权限

v$database
This view lets you access database information. For example, you can check (using log_mode) whether or not the database is in archivelog mode: 
ADPDB>select log_mode from v$database;
LOG_MODE
------------
ARCHIVELOG

checkpoint_change# records the SCN of the last checkpoint. 
switchover_status: can be used to determine if it is possible to perform a switchover operation Only available for physical standby databases. Can be: 
NOT ALLOWED, 
SESSIONS ACTIVE, 
SWITCHOVER PENDING, 
SWITCHOVER LATENT, 
TO PRIMARY, 
TO STANDBY or 
RECOVERY NEEDED. 
See protection modes in data guard for the columns protection_mode and protection_level. 
database_role determines if a database is a primary or a logical standby database or a physical standby database. 
force_logging tells if a database is in force logging mode or not.