Database ID 
The database ID uniquely identifies the data area of a database. The database system creates the database ID during the creation of a new database according to the following pattern:
<computer_name>:<database_name>_<date>_<time>
Example
Database ID of the data area of the DEMODB database on the PARMA computer, which was created on 01/30/2006 at 11:26:33.
PARMA:DEMODB_20060130_112633
When restoring a database, the system uses the database ID to check whether the backups really belong to this database.
The database ID of the data area changes in the following situations:
After initializing the database and then restoring it from a data backup. The data area of the database inherits the database ID that was stored in the backup.
Note that after importing a backup into another database (for example when creating a database copy), the database ID contains the name of the backed-up database. Only after performing the first backup of the restored database is a new database ID assigned, which contains the correct database name and the current time stamp.
After carrying out a data backup in a database with an interrupted backup history (for example after the restart of the database up to a certain time, or after the overwrite mode for the log area was switched on).
The data area of the database gets a new database ID with the current time stamp.
The database system stores the database ID in the following places:
The restart record in the data area (identifies the data area of the database)
The information page of the log area (identifies the log area of the database)
The information page of each backup (identifies the backup)
In the following cases the database ID of data area and log area do not match:
After importing a database backup from another database without initializing the database (and thereby emptying the log area).
In hot standby systems (multiple databases use the same log area)