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ABAP Tutorials -
ABAP Data Dictionary
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Written by Akshata
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Wednesday, 10 September 2008 16:49 |
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The basic objects of the ABAP Dictionary are tables, data elements, and domains. These form the active part of the ABAP Dictionary and contain all the field-related metadata of the R/3 System.
A field is not a dictionary object, but rather is a component of a table. A field cannot exist without a table and only has meaning within that particular table.
Data elements and domains are dictionary objects. Therefore, they can be used by many tables. They specify the characteristics of fields.
 Tables are the objects that actually hold the information in a database. They consist of rows (records) and columns (fields).
For example, table KNA1 stores information about customers. Some of the columns in KNA1 are KUNNR (customer ID number), NAME1 (customer name), and ORT01 (customer city). Each row in KNA1 stores this information for a different customer.
Certain fields in a table are specified as the primary key of that table. The primary key is that field or combination of fields that uniquely identifies a row in the table. In table KNA1, the SAP R/3 client (MANDT) and the customer number (KUNNR) form the primary key.
 The database utility provides the interface between the ABAP Dictionary and the underlying database management system (DBMS). It supports the creation of tables and secondary indices in the database both online and in the background.
Whenever you make a change to a dictionary object that affects the underlying database, the database utility is activated. Usually it works silently behind the scenes, but occasionally the database utility will prompt you for information. This occurs when an error is encountered or when existing data must be converted.
The database utility provides the interface to the DBMS by automatically generating the Data Definition Language (DDL) that the DBMS understands.
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ABAP Tutorials 
