T.CODE: SE36 Logical datbase builder
What is Logical Databases?
Logical Database is an special ABAP program which retrieves data from various tables Which are interrelated and provides a read only view of the data. To read data from a database tables we use logical database. A Logical Database is a hierarchical structure of tables. Logical databases contain Open SQL statements that read data from the database. You do not therefore need to use SQL in your own programs. The logical database reads the program, stores them in the program if necessary, and then passes them line by line to the application program or the function module LDB_PROCESS.
- Use the GET statement to process Logical Databases. LDB consists of logically related tables grouped together used for reading and processing data.
- Preparation of the data records by the L.D.B and reading of the data records in the actual report are accomplished with the command pair - Put and Get.
- The three main elements of LDB are - Structure, Selections, Database Program.
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.
Advantages of Logical DataBases
1.No need of programming for retrieval , meaning for data selection
2.Easy to use standard user interface, have check completeness of user input.
3.It offers an easy-to-use selection screen.
You can modify the pre-generated selection screen to your needs. It offers check functions to check whether user input is complete, correct, and plausible.
4.It offers reasonable data selections.
5.It contains central authorization checks for database accesses.
6.Enhancements such as improved performance immediately apply to all report programs that use the logical database.
7.Less coding is required to retrieve data compared to normal internel tables.
8.Check functions which check that user input is complete, correct,and plausible.
9.Meaningfull data selection.
10.good read access performance while retaining the hierarchical data view determined by the application logic.
Disadvantages of Logical DataBases
1.Fast in case of lesser no. of tables But if the table is in the lowest level of hierarchy, all upper level tables should be read so performance is slower.
2.If you do not specify a logical database in the program attributes,the GET events never occur.
3.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).