DATA DICTIONARY

Data dictionary is the central source of the database management system. The main functionality of the DDIC is to create or alter the tables.

Purpose

Data definitions (metadata) are created and managed in the ABAP Dictionary. The ABAP

Dictionary permits a central description of all the data used in the system without redundancies.

New or modified information is automatically provided for all the system components. This

ensures data integrity, data consistency and data security.

You can create the corresponding objects (tables or views) in the underlying relational database

using these data definitions. The ABAP Dictionary therefore describes the logical structure of the

objects used in application development and shows how they are mapped to the underlying

relational database in tables or views.

The ABAP Dictionary also provides standard functions for editing fields on the screen, for

example for assigning a screen field an input help.

What Information is Stored in the ABAP Dictionary?

The most important object types in the ABAP Dictionary are tables, views, types, domains,

search helps and lock objects.

Tables are defined in the ABAP Dictionary independently of the database. A table

having the same structure is then created from this table definition in the underlying database.

Views are logical views on more than one table. The structure of the view is defined in

the ABAP Dictionary. A view on the database can then be created from this structure.

Types are used in ABAP program. The structure of a type can be defined globally in

ABAP programs. Changes to a type automatically take effect in all the programs using the type.

Lock objects are used to synchronize access to the same data by more than one

user. Function modules that can be used in application programs are generated from the

definition of a lock object in the ABAP Dictionary.

Different fields having the same technical type can be combined in domains. A

domain defines the value range of all table fields and structure components that refer to this

domain.

The ABAP Dictionary also contains the information displayed with the F1 and F4 help for a field

in an input template. The documentation about the field is created for a data element that describes

the meaning of the contents of a table field. The list of possible input values that appears for the

input help is created by a foreign key or a search help.

SAP ABAP TUTORIAL