A Logical Database is a special ABAP program. Basically what a Logical Database does is it combines the contents of certain database tables. A Logical Database needs to be mentioned in the Program attributes, this is done while creating a new program. A program that has a Logical Database linked to it basically has another program working along with it, but this program works like a single program. It makes use of the additional functionality provided by the Logical Database. The processing blocks of the Logical Database are called by the runtime environment in a particular order.
Basically a Logical Database has two functions one is to
Retrieve the data.
A program that uses Logical Database is Event Driven. The most important Event associated with a Logical Database is the GET EVENT. This EVENT is responsible for retrieving the Data.
Example of a Logical Database: F1S
If you are using a Logical Database, even though the Selection screen and the Data Retrieval is carried out by the Logical Database still you can control the selection screen and the depth of the data retrieval process. This can be achieved with the help of the NODE statement.
Once the Logical database is mentioned in the Program Attributes you can then use the GET EVENT in the main program to determine the depth of the data retrieval. Also the NODES statement in your program interacts with the Selection Screen of the Logical Database. You can use the EXIT or CHECK statements to determine the depth of the GET EVENT.