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Wednesday, May 28, 2008

What are logical databases? What are the advantages/ dis-advantages of logical databases?

To read data from a database tables we use logical database. A logical database provides read-only access to a group of related tables to an ABAP/4 program.
Advantages:
i)check functions which check that user input is complete, correct,and plausible.
ii)Meaningful data selection.
iii)central authorization checks for database accesses.
iv)good read access performance while retaining the hierarchical data view determined by the application logic.
Disadvantages:
i)If you donot specify a logical database in the program attributes,the GET events never occur. ii)There is no ENDGET command,so the code block associated with an event ends with the next event statement (such as another GET or an END-OF-SELECTION).



What sort of tables one can use in designing the hierarchy of a LDB ?

Tables which are having Foreign key relations.The structure of Logical Databases relfects the Foreign key dependencies of hierarchical tables in the SAP System.

If you want to improve the response time ( time to access data ) Logical DataBases permits you to achieve this using VIEWS.

Also See :Example : How to create Logical Database

Also See :
What is Logical Database?Logical database in ABAP programming

Also See : How to Generate Query Report ?Example


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