What is Data Dictionary?

Data Dictionary is a central source of information for the data in a information management system. Its main function is to support the creation and management of data definitions (or «metadata»).

ABAP Dictionary 3 levels

Objects in the ABAP Dictionary resided on three levels that support their re-usability. These levels are:

1. Tables and structures
2. Data elements
3. Domains

Lets look into them in detail –

Domains

• Describes the technical characteristics of a table field
• Specifies a value range which describes allowed data values for the fields
• Fields referring to the same domain (via the data elements assigned to them) are changed when a change is made to the domain
• Ensures consistency

Ex. Purchasing document number (EBELN)

Data Elements

• Describes the role played by a field in a technical context
• Fields of same semantic meaning can refer to the same data element
• Contains the field information

Ex. Purchasing document number (EBELN)

Tables

• Represent the Database Tables where data actually resides.
• Tables can be defined independently of the database in the ABAP Dictionary.
• The fields of the table are defined with their (database-independent) SAP ABAP data types and lengths.

Structures

• Are record declarations that do NOT correspond to a Database Table.
• Just like user-defined data type.
• Defined like a table and can then be addressed from ABAP programs.
• Structures contain data only during the runtime of a program.

Aggregated Objects of ABAP Dictionary

Aggregated means consisting of several components. In the ABAP Dictionary, aggregated objects are objects which come from several different transparent tables.

• Views
• Search Help
• Lock Objects

Lets look into them in detail

Views

Views in SAP _ ABAP are used to summarize data which is distributed among several tables.

The data of a view is not actually physically stored. The data of a view is instead derived from one or more other tables.

It is tailored to the needs of a specific application

Search Help

A Search help is a tool to help you search for data records in the system.

An efficient and user-friendly search assists users where the key of a record is unknown

Lock Objects

Simultaneous accessing of the same data record by two users in the SAP system is synchronized by a lock mechanism.

Locks are set and released by calling certain function modules. These function modules are generated automatically from the definition of so-called lock objects in the ABAP/4 Dictionary

Function modules : Enqueue_<obj name> – to lock the table dequeue_<obj name> – to release the lock

Important Transactions

• SE11 : Data Dictionary Initial Screen (SE12 Display only)
• SE13 : ABAP Dictionary : Technical Settings
• SE14 : Database Utility
• SE15 : Repository Information System
• SE16 : Data Browser
• SE17 : General table Display
• SE55 : Table View Maintenance
• SM30 : Table Maintenance