ABAP Data Dictionary
Before we jump directly in to Data Dictionary concept, let us learn something about basic SQL operations. To perform any operation on Data we need to perform two things: Define Data and Manipulate Data. Both of these operations are achieved by SQL [Structured Query Language] operations. SQL is a language that helps us to communicate with our database.
SQL can be, therefore, divided into two parts:
DDL: DATA DEFINITION LANGUAGE
DML: DATA MANIPULATION LANGUAGE
DDL part of ABAP is managed by ABAP Dictionary. Data Dictionary is used to create and manage data definitions (metadata). ABAP Dictionary helps to create user defined types (domain, data elements, structures and table types) which are further utilized by ABAP objects (tables or views).
DML part of ABAP is written using open SQL commands like:
|OPEN SQL COMMAND||DESCRIPTION|
|SELECT||To Read Data from Database|
|INSERT||To Insert Data in Database|
|UPDATE||To Update current Data in Database|
|MODIFY||To Insert/Update Data in Database (whichever applicable)|
|DELETE||To Delete from Database|
Features of ABAP Dictionary:
- DOMAIN: A reusable object that is assigned to a Data Element and it is used to define a value range (F4 Help) and provides technical attributes (Data Type, Number of character, etc).
- DATA ELEMENT: A reusable object that takes attributes of a Domain. It is used to create Field Labels & Field Documentation that appears as field help (F1 Help).
- TYPES [STRUCTURE]: A reusable object that is used to create a global structure. TYPE option in ABAP is also used to create DATA ELEMENTS and TABLE TYPES.
- TABLE TYPES: A TABLE TYPES is used to create global Internal Table. A TABLE TYPE needs a LINE TYPE that acts as the workarea of that Internal Table.
- TABLES: A TABLE is used to create a physical table definition in database. These are defined in ABAP Dictionary independently of the database [that means every Table in independent with respect to other tables and storage].
- VIEWS: It creates logical View of more than one table. By Logical View we mean a view that is presented to the user not that is actually stored in database [also called Physical View].
- SEARCH HELPS: These are the objects that are used to create and assign Input Help (F4 HELP) to screen fields.
- LOCK OBJECTS: These are used to synchronize the access of same data by different users.
Advantages of ABAP Dictionary:
- Data Integrity
- Data Consistency
- Data Security
- Data reusability