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.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.
Friday, December 3, 2010
1. Abap dictionary
A data dictionary is a centralized storage location for information about the data that is stored in a database. This information is often called “metadata” (data about data).
SAP’s data dictionary is called the ABAP Dictionary.
A data dictionary provides answers to questions such as:
What data is contained in the database?
What are the attributes of this data: name, length, format, etc.?
What relationships exist among different data objects?
The ABAP Dictionary:
Enforces data integrity
Manages data definitions without redundancy
Is tightly integrated with the rest of the ABAP Workbench
When data integrity rules are defined in the ABAP Dictionary, the system automatically prevents the entry of invalid data. Defining the data integrity rules at the dictionary level means they only have to be defined once, rather than in each program that accesses that data.
The following are examples of data lacking integrity:
-> A date field with a month value of 13
-> An order assigned to a customer number that doesn’t exist
Additionally, the system provides easy navigation between development objects and dictionary definitions. For example, if you can double-click on the name of a dictionary object in your program code, the system will take you directly to the definition of that object in the ABAP Dictionary.
When a dictionary object is changed, a program that references the changed object will automatically reference the new version the next time the program runs. Because ABAP is interpreted, it is not necessary to recompile programs that reference changed dictionary objects.
SAP’s data dictionary is called the ABAP Dictionary.
A data dictionary provides answers to questions such as:
What data is contained in the database?
What are the attributes of this data: name, length, format, etc.?
What relationships exist among different data objects?
The ABAP Dictionary:
Enforces data integrity
Manages data definitions without redundancy
Is tightly integrated with the rest of the ABAP Workbench
When data integrity rules are defined in the ABAP Dictionary, the system automatically prevents the entry of invalid data. Defining the data integrity rules at the dictionary level means they only have to be defined once, rather than in each program that accesses that data.
The following are examples of data lacking integrity:
-> A date field with a month value of 13
-> An order assigned to a customer number that doesn’t exist
Additionally, the system provides easy navigation between development objects and dictionary definitions. For example, if you can double-click on the name of a dictionary object in your program code, the system will take you directly to the definition of that object in the ABAP Dictionary.
When a dictionary object is changed, a program that references the changed object will automatically reference the new version the next time the program runs. Because ABAP is interpreted, it is not necessary to recompile programs that reference changed dictionary objects.
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