SAP ABAP Interview Questions and Learnings

DATA DICTIONARY .

Type of a table or structure
The table type determines how the logical table description defined in the ABAP/4 Dictionary is reproduced on the database. There are the following table types:
1. transparent table
2. structure
3. append structure
For internal purposes, such as storing control data or update texts, there are in addition the following table types:

1. pooled table
2. cluster table
3. generated view structure

Transparent table There is a physical table on the database for each transparent table. The names of the physical tables and the logical table definition in the ABAP/4 Dictionary correspond. All business data and application data are stored in transparent tables.

Structure No data records exist in the database for a structure. Structures are used for the interface definition between programs or between screens and programs.

Append structure An append structure defines a set of fields which belong to another table or structure but which are treated in the correction administration as its own object. Append structures are used to support modifications.

Pooled table Pooled tables can be used to store control data (e.g. screen sequences, program parameters or temporary data). Several pooled tables can be combined to form a table pool. The table pool corresponds to a physical table on the database in which all the records of the allocated pooled tables are stored.

Cluster table Cluster tables contain continuous text, for example, documentation. Several cluster tables can be combined to form a table cluster. Several logical lines of different tables are combined to form a physical record in this table type. This permits object-by-object storage or object-by-object access. In order to combine tables in clusters, at least parts of the keys must agree. Several cluster tables are stored in one corresponding table on the database.

Generated view structure In activation a structure is generated for a view. This structure serves as interface for the runtime environment. It does not generally appear in the ABAP/4 Dictionary.

What is a Data Class?

The Data class determines in which tablespace the table is stored when it is created in the database. What is a Size Category? The Size category describes the probable space requirement of the table in the database. 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 frequnetly)
- APPL2 - Organisational data (customizing data that is entered when system is
configured and then rarely changed)

What are control tables?

The values specified for the size category and data class are mapped to database-specific values via control tables.

What is the function of the transport system and workbench organiser?

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.

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).

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).

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.

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.

What are the Data types of the external layer?
ACCP, CHAR, CLNT, CUKY,CURR, DATS, DEC, FLTP, INT1,INT2, INT4, LANG, LCHR,LRAW, NUMC, PREC, QUAN,RAW ,TIMS, UNIT, VARC.

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 or counter field (packed; implementation depends on hardware platform). S: Time stamp YYYYMMDDHHMMSS. T: Time of day HHMMSS. V: Character string of variable length, length is given in the first two bytes. X: Hexadecimal (binary) storage.

How can we set the tablespaces and extent sizes ?
You can specify the extent sizes and the tablespace (physical storage
area in the database) in which a transparent table is to be stored by setting the size category and data class.

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 .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 ?

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 software development
- Support form documentation
- Ensuring that the data definitions are flexible and up-to-date.

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 table 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.

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 requiremnets
- table access behaviour
- buffering required
- changes to entries logged

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. - determines how the table behaves when it is first installed, at upgrade, when it is transported, and when a client copy is performed.

What is the maximum number of structures that can be included in a table or structure
- Nine.

What are the two methods of modifying Sap standard tables ?
- Append Structures and
- Customizing Includes.


What is the difference between a Substructure and an Append Structure ?
- In case of a substructure, the reference originates in the table itself, in the forma of a statement .include... . - In case of an append structure, the table itself remains unchanged and the refrence originates in the append structure.
What are the two ways for restricting the value range for a domain ? - By specifying fixed values.
- By stipulating a value table.

What is a Match Code ?

Match Code is a tool to help us to search for data records in the system. Match codes are an efficient and user-friendly search aid where key of a record is unknown. What are the two levels in defining a Match Code ?
- Match Code object
- Match Code Id.

What is the maximum number of match code Id's that can be defined for one Match code object ?
- 36. A match code Id is a one character ID which can be a letter or a number.

Can we define our own Match Code ID's for SAP Matchcodes ?
Yes, the numbers 0 to 9 are reserved for us to create our own Match Code IDs for a SAP defined Matchcode object.

What is an Update type with reference to a Match code ID?
If the data in one of the base tables of a matchcode ID changes, the matchcode data has to be updated. The update type stipulates when the matchcode is to be updated and how it is to be done. The update type also specifies which method is to be used for Building matchcodes . You must specify the update type when you define a matchcode ID.

What are conversion routines ?
- Non standard conversions from display format to sap internal format and vice-versa are implemented with so called conversion routines.
Aggregated Objects Views, matchcodes, and lock objects are also called aggregate objects because they are formed from several related tables.
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