Logical Databases and usage

Logical Databases and usage

• Database within a database, but logically stored within existing (physical) tables.

• Logical databases are special ABAP programs that retrieve data and make it available to application programs. The most common use of logical databases is still to read data from database tables by linking them to executable ABAP programs.
• 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 using an interface work area.

function module ( SE 37 ) : LDB_PROCESS

Logical Databases -Views of Data

• A logical database provides a particular view of database tables in the R/3 System. It is always worth using logical databases if the structure of the data that you want to read corresponds to a view available through a logical database.
• 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. Some of these dependencies form tree-like hierarchical structures. Logical databases read data from database tables that are part of these structures.

• The diagram illustrates how the R/3 System might represent the structure of a company. A logical database can read the lines of these tables one after the other into an executable program in a sequence which is normally defined by the hierarchical structure. The term logical database is sometimes used to mean not only the program itself, but also the data that it can procure.

Tasks of Logical Databases

1. Reading the same data for several programs.
2. Defining the same user interface for several programs.
3. Central authorization checks.
4. Improving performance

Structure of a Logical Database

Reading Data

Event Key Words: Overview

Interaction of Logical Databases and Report

Ex :

Report (SE 38)-Driven Reading of Vendor Master Data

The STOP Statement

Logical Database vs. Select

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