There are two ways of using a logical database:
1) By linking it with an executable program
This allows you to call several logical databases from any ABAP program, nested in any way.
LDB's 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 .
The data structure in a logical database is hierarchical. Many tables in the R/3 System are linked to each other using foreign key relationships.
After each table line is transferred, a GET event occurs and the executable program (report) is able to process it by activating the appropriate processing block. If you do not specify a logical database in the program attributes, the GET events never occur.
In the processing blocks after the GET events, you only have to specify the statements for analyzing the data and writing the results to the screen.
T-code for LDB is SE36.
Below is an example of how the structure of ADA logical database is defined in the hierarchy.
1. Logical databases have a built-in selection screen.You can modify the pre-generated selection screen as per your program needs.
2. It offers check functions to check whether user input is complete, correct, and plausible.
3. It offers reasonable data selections.
4. It contains central authorization checks for database accesses.
5. Good read access performance (for example, with views) while retaining the hierarchial data view determined by the application logic.