A database instance is a set of memory structures that manage database files. A database is a set of physical files on disk created by the CREATE DATABASE statement. The instance manages its associated data and serves the users of the database.
Every running Oracle database is associated with at least one Oracle database instance. Because an instance exists in memory and a database exists on disk, an instance can exist without a database and a database can exist without an instance.
Read More →
SHUTDOWN ABORT
This mode is intended for emergency situations, such as when no other form of shutdown is successful. This mode of shutdown is the fastest. However, a subsequent open of this database may take substantially longer because instance recovery must be performed to make the data files consistent.
SHUTDOWN IMMEDIATE
This mode is typically the fastest next to SHUTDOWN ABORT. Oracle Database terminates any executing SQL statements and disconnects users.
Read More →
sudo apt-get install xinit sudo apt-get update sudo apt-get install xfce4 ubuntu中输入startx