Error Solution Implementing SAP GST Notes-2405502

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File Name Business_Place_Screen_Regeneration_steps.pdf

Interview Questions

1.     Difference Between Type ,Data ,Types & Field-Symbol   :

TYPE   STATEMENT you can define structure which have no physical memory.

DATA STATEMENT you can define structure with physical memory with predefined data objects.

TYPES describes what data should look like.

FIELD-SYMBOL are similar to dereferenced pointers in C. While using the field-symbol, system uses the same memory allocated to that particular field in the record instead of moving it to work area and processing. They do not physically reserve space for a field, but point to its contents.

2. Call by value and Call by Reference.

Call by reference new memory is not allocated for the value. Instead, a pointer to the original memory location is passed. All references to the parameter are references to the original memory location. Changes to the variable within the subroutine update the original memory location immediately.

Example.  Data f1 value 'A'.
                Perform s1 using f1.
               Write / f1.
                    Form s1 using p1.
                    p1 = 'X'.
                  Endform.

O/P X

Call By value new memory is allocated for the value. This memory is allocated when the subroutine is called and is freed when the subroutine returns. Therefore, references to the parameter are thus references to a unique memory area that is known only within the subroutine; the original memory location is separate

Example.  Data f1 value 'A'.
                     Perform s1 using f1.
                Write / f1.
                     Form s1 using value( p1).
                     p1 = 'X'.
                     Write p1.
                   Endform.
O/P   X             A.

3. Types of Internal table. 

Standard tables have an internal linear index. The key of a standard table is always non-unique. You cannot specify a unique key. This means that standard tables can always be filled very quickly, since the system does not have to check whether there are already existing entries.  

Sorted tables are always saved sorted by the key. They also have an internal index. The system can 
access records either by using the table index or the key. The response time for key access is logarithmically proportional to the number of table entries, since the system uses a binary search. The key of a sorted table can be either unique or non-unique. When you define the table, you must specify whether the key is to be UNIQUE or NON-UNIQUE. Standard tables and sorted tables are known generically as index tables. 

Hashed Table defines the table as one that is managed with an internal hash procedure. You can imagine a hashed table as a set, whose elements you can address using their unique key. Unlike standard and sorted tables, you cannot access hash tables using an index. All entries in the table must have a unique key.

4. Search

           Linear search: which will search line by line.

          

           SORT TKOMV BY KNUMV KPOSN KSCHL.

READ TABLE TKOMV WITH KEY KNUMV = GT_VBAK-KNUMV KPOSN = GT_VBAP-POSNR KSCHL ='PR00'.

Binary Search: which will directly go to n1/2 record if it matches the condition then ok otherwise if the N1/2 record is greater than the searching value it will ignores the 2nd half of the records, again from the rest of 1st half records it will calculate the middle record and then it will checks for the condition, in this way it will work, it means at a single iteration it will eliminates half of the records from the search criteria.

SORT TKOMV BY KNUMV KPOSN KSCHL.

              READ TABLE TKOMV WITH KEY KNUMV = GT_VBAK-KNUMV KPOSN = GT_VBAP-POSNR     KSCHL ='PR00 line BINARY SEARCH.

5.     How many breakpoints can be in a program?
      There is no fixed Number of breakpoints that to be kept in program but debugging screen can display only 30 breakpoints.

6.     Difference Watch point between breakpoint ?
      Breakpoint is that you specified a point a row of program to debug.
      Watch point is that you specified a condition to debug.

7.     Types of Tables.

Transparent table (One to one relation) this table in data dictionary equal to one table in data base.

I.e. When u create one transparent table in ABAP dictionary one table will be created in Database (Typically Oracle, U can have others also) with same name (Both table and fields). Basically used to hold application data. EG: EKKO, VBAK etc.

Pooled table: (Many to one relationship) many tables in ABAP dictionary equal to one table pool in database. Basically used to hold system data and customization data. One table pool contains large number of pooled tables having data of around 100 records each. 

Cluster tables: (Many to one relationship) many tables in ABAP dictionary equal to one table cluster in database. Basically used to hold application data. One table cluster contains few number of cluster tables having data of around large quantities. (In lakhs) e.g.: CDPOS, BSEG etc.

8.     Difference Delivery class and Data Class

                Delivery class controls the transport of table data for installation, upgrade, client copy and when transporting  
                between customer systems. The delivery class of a table determines whether SAP or the customer is 
                responsible for maintaining the data in the table. It also determines how the table behaves in a client copy or 
                upgrade.

           Data class determines the physical area of the database (table space) in which the table is created. 
                You set the data class in the technical settings for the table. Each data class corresponds to a physical
                area  in  which all the tables assigned to this data class are stored. There are the following data classes:

9.     Difference between Primary & Secondary Index?

Primary Index: An index used to improve performance on the combination of columns most frequently used to access rows in a table. The index that controls the current processing order of a file. It maintains an index on the primary key.

Secondary indexes are maintained by the system and are invisible to the user. Any column(s) may be specified as a secondary index, except columns declared using a LOB data type. Maximum number of indexes for a table can be 9.Access using %_HINTS ORACLE ‘INDEX ("SPFLI" "SPFLI~001")'. 

10. Size Category in table defines the expected space required for the table in the database. You can choose a size category from 0 to 4 for your table. A certain fixed memory size in the database, which depends on the database system used, is assigned to each category.

11. Update Function Module is used for SAP Logical Unit of Work. These function modules are triggered when an Explicit or Implicit COMMIT WORK is encountered.

               Steps       CALL FUNCTION    FM_NAME IN UPDATE TASK

                                   TABLES
                                   it_xvbkd = xvbkd.

Update with immediate start: These functions can be restarted by the update task in case of errors. Set this option for high priority functions that run in a shared (SAP LUW).

Update with immediate start, no restart: Set this option for high priority ("V1") functions that run in a shared (SAP LUW). These functions may not be restarted by the update task

Update with delayed start: Set this option for low priority ("V2") functions that run in their own update transactions. These functions can be restarted by the update task in case of errors.

Debugging: Switch on the debugger....go to Settings -> Display/Change Debugger Setting in that check the check box for 'Update Debugging'.

             Background Task   CALL FUNCTION    FM_NAME IN Background TASK
                                            TABLES
                                           it_xvbkd = xvbkd.

It will be assigned to a separate LUW.We can see this LUW registered in t-code SM58 and execute, debug and delete manually.  

12. ABAP memory and SAP memory

SAP memory is a memory area to which all main sessions within a SAP GUI have access. You can use SAP memory either to pass data from one program to another within a session, or to pass data from one session to another.  Application programs that use SAP memory must do so using SPA/GPA parameters (also known as SET/GET parameters). These parameters can be set either for a particular user or for a particular program using the SET PARAMETER statement. Other ABAP programs can then retrieve the set parameters using the GET PARAMETER statement. The most frequent use of SPA/GPA parameters is to fill input fields on screens.

ABAP memory is a memory area that all ABAP programs within the same internal session can access using the EXPORT and IMPORT statements. Data within this area remains intact during a whole sequence of program calls. To pass data to a program which you are calling, the data needs to be placed in ABAP memory before the call is made. The internal session of the called program then replaces that of the calling program. The program called can then read from the ABAP memory. If control is then returned to the program which made the initial call, the same process operates in reverse.

13. Events of Report

·         Initialization

·         At selection-screen

·         At selection screen on (output, value request, help request)

·         Start of selection

·         End of selection

·         Top of page

·         End of page

14. Difference between AT SELECTION-SCREEN and AT SELECTION-SCREEN OUTPUT?

AT SELECTION-SCREEN is the PAI of the selection screen whereas AT SELECTION-SCREEN OUTPUT is the PBO of the selection screen.

15. What is the need of END-OF-SELECTION event in ABAP reporting?

END-OF-SELECTION event is triggered in type executable programs once the logical database has finished reading all data and before the list processor is started. It tells the server that all the database reading is completed and no further reading is going to take place.

16. Lock Concept 

Database Locks & SAP Locks 

Lock objects are use in SAP to avoid the inconsistency at the time of data is being insert/change into database.

                SAP Provide three type of Lock objects. 

Read Lock (Shared Locked) protects read access to an object. The read lock allows other transactions read access but not write access to the locked area of the table.

Write Lock (Exclusive lock) protects write access to an object. The write lock allows other transactions neither read nor write access to the locked area of the table.

Enhanced write lock (exclusive lock without cumulating) works like a write lock except that the enhanced write lock also protects from further accesses from the same transaction.

Mode of Locks.

Shared lock	S (Shared)	Several users (transactions) can access locked data at the same time in display mode. A request for another shared lock is accepted, even if it comes from another user. An exclusive lock set on an object that already has a shared lock will be rejected.
Exclusive lock	E (Exclusive)	An exclusive lock protects the locked object against all types of locks from other transactions. Only the same lock owner can reset the lock (accumulate).
Exclusive but not cumulative lock	X (exclusive non-cumulative)	Exclusive locks can be requested several times from the same transaction and are processed successively. In contrast, exclusive but not cumulative locks can be called only once from the same transaction. Each further lock request will be rejected.
Optimistic lock	O (Optimistic)	Optimistic locks initially behave like shared locks and can be converted into exclusive locks

17. Views

The data of a view is derived from one or more tables, but not stored physically. These differ in the way in which the view is implemented and in the methods permitted for accessing the view data.

·     Database views are implemented with an equivalent view on the database. A database view provides an application-specific view on such distributed data. Database views implement an inner join

·       Projection Views are used to hide fields of a table. This can minimize interfaces; for example when you access the database, you only read and write the field contents actually needed. A projection view contains exactly one table. You cannot define selection conditions for projection views. It is also possible to access pooled tables or cluster tables with a projection view.

·       Help Views The selection method of a search help is either a table or a view. If you have to select data from several tables for the search help, you should generally use a database view as selection method. However, a database view always implements an inner join. If you need a view with outer join for the data selection, you have to use a help view as selection method.

18. OOPs  Concept

·         Definition of class:

 A Class is a Template of objects which can handle more than one characteristic. Classes don’t have                      any data it has attributes and methods

·         Definition of Objects:
        Object is a real-time entity in the world.  It is the instances on classes and holds some data

·         Definition of Association:
         Relating two classes or relation between two classes is called as Association.

·         Definition of Aggregation
         One class using the instances on other class is known as Aggregation.

·         Definition of Composition
         when one class data is related or will affect  other class data is known as composition E.g.  when one class data is deleted the data pertaining to that in another class will be deleted.Should have relationship in such a form.

·         Definition of Abstraction:
          Extracting the essential details or data while ignoring the unwanted data.

·         Definition of  Encapsulation:
          Enclosing all parts of Abstraction in a container. It is often know as Information Hiding Hides how information how the implementation is done. Shows only the necessary information.

19. Instance and Static

• Static Methods: these methods can be called without creating an object for the class. These methods can be directly called using the class name like. If u declares one attribute as a static then we can use that attribute through class name, that attribute is independent of that object. You declare static methods using the CLASS-METHODS statement. That means memory allocation for the attribute is only once.
• Instance Methods: These methods can be only called using the object of the class. If u declares one attribute as an instance then we can use that attribute through object name, that attribute is dependent of that object. You declare instance methods using the METHODS statement.

20. Constructor & Static-Constructor.

The Instance constructor of a class is the predefined instance method CONSTRUCTOR.
·         Constructor's signature can have only importing parameters or exceptions.
·         Instance Constructor is a special instance method can access the Instance Variables and Static                 Variables.  This method is used to set the default values in a class. 

      The Static constructor of a class is the predefined static method CLASS_CONSTRUCTOR.

·         The constructor's signature cannot have importing   parameters or exceptions.

·         The static constructor is as special static method can access the static variables.

·         These are used to set default values for the global attributes irrespective of instances

21. Type  of classes

·         Final
·         Static
·         Persistence
·         Abstract
·         Test Class 

22. Types of Methods.

·         Final   
·         Static
·         Abstract
·         Instance

23. Visibility in class with sequence

·         Private
·         Protected
·          Public

24. Difference between static and instance variables

Static attributes:

·         The attributes are created only once.
·         That means memory allocation for the attribute is only once.
·         We can call next time the same attribute by using object then the same memory space is referred.
·         We can change the value in the memory.

Instance attributes:

·        These attributes are created for every time.
·        That means for each and every call statement, the attribute creates a new memory location at every time.

25. Exception Classes in Object Oriented Programming

Exceptions are the errors that occur during the execution of the program that interrupts the normal flow of control. 

All exception classes are inherited from global class CX_ROOT and the classes that are directly inherited are

·         CX_STATIC_CHECK:

It is checked by both the compiler and runtime system. If any exception of this category found and not handled locally inside the procedure, it has been declared in the RAISING clause of the procedure’s interface

TRY.

    RAISE EXCEPTION TYPE Exception class name
                EXPORTING msgv1 = 'For'
                                      msgv2 = 'Handling'
                                      msgv3 = 'Exceptions '
                                      msgv4 = 'In Program '.

  CATCH Exception class name INTO CX_root Object.

ENDTRY.

·         CX_DYNAMIC_CHECK:

It is checked only at runtime system. When the exceptions tries to leave a procedure that it has been declared in RAISING class. Generally all system exceptions like CX_SY_ZERO_DIVIDE will come under these exceptions

·         CX_NO_CHECK:

This type of exceptions will be choose if the exception can occur almost everywhere. These exceptions are always implicitly declared.

26. Casting

·         Assigning/copying the instance of sub class to super class instance is called Narrowing Cast.

·         Assigning/copying the instance of super class to the sub class instance is called Widening Cast

27. Deferred: Addition makes a class known provisionally in the program.

28. Can refer to a class without defining it?

Yes, by Using Deferred keyword.

29. What are logical units of work?

The main purpose of the logical unit of work is to ensure data consistency in the R/3 systems.Two  Types of LUW.

·         Database LUW is work unit consisting of database operations (INSERT, UPDATE, MODIFY & DELETE) that it used to make the database changes.  The final database LUW of a SAP LUW is used to make the changes to the database, the changes to the database is not made until after the database commit. The database LUW is executed in a special kind of work process called the update work process.

·         SAP LUW is a logical unit work that spans over several dialog steps. Let us consider a complex R/3 transaction of n screens; where each screen has its own DB LUW involving database operations and are logically related to each other. It is important that the changes to the database for this complex transaction must be made all at once or it must be rolled back all for the data consistency; that is where the SAP LUW becomes critical in maintaining a logical relationship between several DB LUWs (dialog phases) & making all the changes to the database in the final DB LUW. SAP LUW uses the bundling technique to achieve the same. There are several possibilities of bundling technique and one of them is bundling the database changes using a function module call in the UPDATE TASK.

30. What are Concrete and Non-Concrete methods?

Abstract
Interface