1. What are the layers of data description in R/3?
- The external layer.
- The ABAP/4 layer.
- The database layer.
2. Define external layer?
The external layer is the plane at which the user sees and interacts with the data, that is, the data format in the user interface. This data format is independent of the database system used.
3. Define ABAP/4 layer?
The ABAP/4 layer describes the data formats used by the ABAP/4 processor.
4. Define Database layer?
The database layer describes the data formats used in the database.
5. What is a Data Class?
The Data class determines in which table space the table is stored when it is created in the database.
6. What is a Size Category?
The Size category describes the probable space requirement of the table in the database.
7. How many types of size categories and data classes are there?
There are five size categories (0-4) and 11 data classes only three of which are appropriate for application tables:
APPL0 - Master data (data frequently accessed but rarely updated).
APPL1 - Transaction data (data that is changed frequently).
APPL2 - Organizational data (customizing data that is entered when system is configured and then rarely changed).
The other two types are:
- USR
- USR1 – Intended for customer’s own developments.
8. What are control tables?
The values specified for the size category and data class are mapped to database-specific values via control tables.
9. What is the function of the transport system and workbench organizer?
The function of the transport system and the Workbench Organizer is to manage any changes made to objects of the ABAP/4 Development Workbench and to transport these changes between different SAP systems.
10. What is a table pool?
A table pool (or pool) is used to combine several logical tables in the ABAP/4 Dictionary. The definition of a pool consists of at least two key fields and a long argument field (VARDATA).
11. What are pooled tables?
These are logical tables, which must be assigned to a table pool when they are defined. Pooled tables can be used to store control data (such as screen sequences or program parameters).
12. What is a table cluster?
A table cluster combines several logical tables in the ABAP/4 Dictionary. Several logical rows from different cluster tables are brought together in a single physical record. The records from the cluster tables assigned to a cluster are thus stored in a single common table in the database.
Read also the Difference between a check table and a value table
13. How can we access the correction and transport system?
Each time you create a new object or change an existing object in the ABAP/4 Dictionary, you branch automatically to the Workbench Organizer or correction and transport system.
14. Which objects are independent transport objects?
Domains, Data elements, Tables, Technical settings for tables, Secondary indexes for transparent tables, Structures, Views, Matchcode objects, Matchcode Ids, Lock objects.
15. How is conversion of data types done between ABAP/4 & DB layer?
Conversion between ABAP/4 data types and the database layer is done within the database interface.
16. How is conversion of data types done between ABAP/4 & external level?
Conversion between the external layer and the ABAP/4 layer is done in the SAP dialog manager DYNP.
17. What are the Data types of the external layer?
ACCP, Char, CLNT, CUKY, CURR, DATS, DESC, FLTP, INT1, INT2, INT4, LANG, LCHR, LRAW, NUMC, PREC, QUAN, RAW, TIMS, UNIT,VARC.
18. What are the Data types of the ABAP/4 layer?
Possible ABAP/4 data types:
C: Character.
D: Date, format YYYYMMDD.
F: Floating-point number in DOUBLE PRECISION (8 bytes).
I: Integer.
N: Numerical character string of arbitrary length.
P: Amount of counter field (packed; implementation depends on h/w platform).
S: Time Stamp YYYYMMDDHHMMSS.
V: Character string of variable length, length is given in the first two bytes.
X: Hexadecimal (binary) storage.
19. How can we set the table spaces and extent sizes?
You can specify the extent sizes and the table space (physical storage area in the database) in which a transparent table is to be stored by setting the size category and data class.
20. What is the function of the correction system?
The correction system manages changes to internal system components. Such as objects of the ABAP/4 Dictionary.
21. What are local objects?
Local objects (Dev class$TMP) are independent of correction and transport system.
22. What is a Development class?
Related objects from the ABAP/4 repository are assigned to the same development class. This enables you to correct and transport related objects as a unit.
23. What is a data dictionary?
Data Dictionary is a central source of data in a data management system. Its main function is to support the creation and management of data definitions. It has details about
- What data is contained?
- What are the attributes of the data?
- What is the relationship existing between the various data elements?
24. What functions does a data dictionary perform?
In a data management system, the principal functions performed by the data dictionary are
- Management of data definitions.
- Provision of information for evaluation.
- Support for s/w development.
- Support form documentation.
- Ensuring that the data definitions are flexible and up-to-date.
25. What are the features of ABAP/4 Dictionary?
The most important features are:
- Integrated to aABAP/4 Development Workbench.
- Active in the runtime environment.
26. What are the uses of the information in the Data dictionary?
The following information is directly taken from the Data dictionary:
- Information on fields displayed with F1 help.
- Possible entries for fields displayed with F4 help.
- Matchcode and help views search utilities.
27. What are the basic objects of the data dictionary?
- Tables
- Domains
- Data elements
- Structures
- Foreign Keys
28. What are the aggregate objects in the data dictionary?
- Views
- Match codes
- Lock objects.
29. In the ABAP/4 Dictionary Tables can be defined independent of the underlying database (T/F).
True.
30. ABAP/4 Dictionary contains the Logical definition of the table.
Also read The Different Types of SAP Tables
31. A field containing currency amounts (data type CURR) must be assigned to a reference table and a reference field. Explain.
As a reference table, a system containing all the valid currencies is assigned or any other table, which contains a field with the currency key format. This field is called as reference field. The assignment of the field containing currency amounts to the reference field is made at runtime. The value in the reference field determines the currency of the amount.
32. A field containing quantity amounts (data type QUAN) must be assigned to a reference table and a reference field. Explain?
As a reference table, a system table containing all the valid quantity units is assigned or any other table, which contains a field with the format or quantity units (data type UNIT). This field is called as reference field.
The assignment of the field containing quantity amounts to the reference field is made at runtime. The value in the reference field determines the quantity unit of the amount.
33. What is the significance of Technical settings (specified while creating a table in the data dictionary)? 
By specifying technical settings we can control how database tables are created in the database. The technical settings allows us to
- Optimize storage space requirements.
- Table access behaviour.
- Buffering required.
- Changes to entries logged.
34. What is a Table attribute?
The table’s attributes determine who is responsible for maintaining a table and which types of access are allowed for the table. The most important table attributes are:
- Delivery class.
- Table maintenance allowed.
- Activation type.
35. What is the significance of Delivery Class?
- The delivery class controls the degree to which the SAP or the customer is responsible for table maintenance.
- Whether SAP provides the table with or without contents.
- Determines the table type.


Serkan AKKAVAK
Computer Engineer
ABAP Developer & SAP MM SD Consultant
Contact : serkurumsal@yandex.com