1-introduction to abap

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Introduction to ABAP

ABAP stands for Advanced Business Application Programming. It is a programming

language for developing applications for the SAP R/3 system.

The latest version of ABAP is called ABAP Objects and supports object-oriented

programming. SAP will run applications written using ABAP/4, the earlier ABAP

version, as well as applications using ABAP Objects.

Data Types

Syntax to declare a variable in ABAP -

DATA Variable_Name Type Variable_Type

Example:

DATA employee_number Type I.

The following is a list of Data Types supported by ABAP

Data

Type

Initial field

length

Valid field

length

Initial

value

Meaning

Numeric types

I 4 4 0 Integer (whole number)

F 8 8 0 Floating point number

P 8 1 - 16 0 Packed number

Character types

C 1 1 - 65535 ' ... ' Text field(alphanumeric

characters)

D 8 8 '00000000' Date field(Format:



YYYYMMDD)

N 1 1 - 65535 '0 ... 0' Numeric text field(numeric

characters)

T 6 6 '000000' Time field(format:

HHMMSS)

Hexadecimal type

X 1 1 - 65535 X'0 ... 0' Hexadecimal field

Processing Data - Assigning Values

a=16.

move 16 to a.

write a to b.

- Arithmetic Operations

compute a = a*100.

Control Statements

Following control statements can be used - - If ... EndIf Loop

if [not] exp [ and / or [not] exp ].

........

[elseif exp.

.......]

[else.

.......]

Endif.

- Case statement



Case variable.

when value1.

.........

when value2.

.........

[ when others.

.........]

Endcase.

Do.

-While loop

While <logical expression>.

.....

.....

Endwhile.

- Do loop

Do <n> times.

.....

.....

Enddo.

Logical Operator

A list of logical operators

GE or >=

GT or >

LE or <=

LT or <

EQ or =

NE or <>

ABAP/4 Editor



Finally, here is where you will spend most of your time as a developer creating /

modifying programs. Transaction SE38

ABAP Data Dictionary TutorialA data dictionary is a central source of information for the data in a information

management system. Its main function is to support the creation and management of

data definitions (or "metadata").

What is Data dictionary used for?

Management of data definitions

Provision of information for evaluations Support for software development

Support for documentation

Ensuring that data definitions are flexible and up-to-date



Objects in the ABAP Dictionary resided on three levels that support their re-usability.

These levels are:

1. Tables and structures

2. Data elements

3. Domains

Let’s look into them in detail -

Domains

Describes the technical characteristics of a table field

Specifies a value range which describes allowed data values for the fields

Fields referring to the same domain (via the data elements assigned to them)

are changed when a change is made to the domain

Ensures consistency

Ex. Purchasing document number (EBELN)



Data Elements

Describes the role played by a field in a technical context

Fields of same semantic meaning can refer to the same data element

Contains the field information

Ex. Purchasing document number (EBELN)



Tables

Represent the Database Tables where data actually resides.

Tables can be defined independently of the database in the ABAP Dictionary.

The fields of the table are defined with their (database-independent) SAP

ABAP data types and lengths.



Structures

Are record declarations that do NOT correspond to a Database Table.

Just like user-defined data type.

Defined like a table and can then be addressed from ABAP programs.

Structures contain data only during the runtime of a program.



Aggregated Objects of ABAP Dictionary

Aggregated means consisting of several components. In the ABAP Dictionary,

aggregated objects are objects which come from several different transparent tables.

1. Views

2. Search Help

3. Lock Objects

Lets look into them in detail

Views

Views in SAP _ ABAP are used to summarize data which is distributed among

several tables

The data of a view is not actually physically stored. The data of a view is

instead derived from one or moreother tables

It is tailored to the needs of a specific application



Search Help

A Search help is a tool to help you search for data records in the system

An efficient and user-friendly search assists users where the key of a record is

unknown



Lock Objects Simultaneous accessing of the same data record by two users in the SAP

system is synchronized by a lock mechanism.

Locks are set and released by calling certain function modules. These function

modules are generated automatically from the definition of so-called lock objects in

the ABAP/4 Dictionary

Function modules : Enqueue_<obj name> - to lock the table dequeue_<obj name> -

to release the lock



Important Transactions

SE11 : Data Dictionary Initial Screen (SE12 Display only)

SE13 : ABAP Dictionary : Technical Settings

SE14 : Database Utility

SE15 : Repository Information System

SE16 : Data Browser

SE17 : General table Display

SE55 : Table View Maintenance

SM30 : Table Maintenance

Modularity in ABAP:Macro,Include,Subroutines,Function

Modules & GroupsWhen you modularize source code, you place a sequence of ABAPstatements in a

module. Then, instead of placing all of the statements in your main program, you just

call the module.When the program is generated, the source code in the modularization

unit is treated as though it were actually physically present in the main program.

Need of Modularization

Improve the structure of the program.



Easy to read the code

Easy to maintain the code

Avoid redundancy and promotes code reuse

Various Modularization Techniques

Use of Macros

Use of include files

Subroutines

Function Modules

Let’s look into each of them in detail :

SAP- ABAP MacroIf you want to reuse the same set of statements more than once in a program, you can

include them in a macro. You can only use a macro within the program in which it is defined, and it can only be

called in lines of the program following its definition.

Macros can be useful for long calculations or complex WRITE statements.

Syntax

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DEFINE <macro_name>

'Macro Statements

END-OF-DEFINITION

Macros can use Parameters & N where N = 1,2,3...

Example:-

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DATA: number1 TYPE I VALUE 1.

DEFINE increment.

ADD 1 to &1.

WRITE &1.

END-OF-DEFINITION.

Increment number1.

WRITE number1.

Output: 2



Include ProgramsInclude Programs are solely for modularizing source code, and have no parameter

interface. Include programs allow you to use the same source code in different

programs. They can be useful if you have lengthy data declarations that you want touse in different programs.

Syntax

1 Include <include program Name>

Points to Note

Include programs cannot call themselves.

Include programs must contain complete statements.

Example:

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INCLUDE ZILX0004.

WRITE: / 'User', SY-UNAME,/ 'Date', SY-DATUM.

================================

PROGRAM ZRPM0001.

INCLUDE ZILX0004.

SubroutinesSubroutines are procedures that you can define in any ABAP program and also call

from any program. Subroutines are normally called internally, that is, they contain

sections of code or algorithms that are used frequently locally. If you want a function

to be reusable throughout the system, use a function module.

Syntax-

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FORM <Subroutine> [<pass>].

<Statement block>.

ENDFORM.

<Subroutine> = Name of the subroutine

<pass> = Parameters being passed

Types of Subroutines

1.

Internalo

Subroutine defined in same program being called.



o Can access all the data objects declared in the main ABAP/4 program.

2. External

o Subroutine defined outside the program being called.

o Need to use the <pass> option or declare data objects in common parts

of memory.

Calling a Subroutine I nternal Subroutines

1 PERFORM <subroutine> [<pass>]

<subroutine> = Name of the subroutine

<pass> = Parameters being passed

Data declared in main program is automatically available.

External Subroutines

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PERFORM <subroutine>(<Program>) [<pass>].

PERFORM <subroutine> (<Program>) [<pass>] [IF FOUND].

PERFORM (<subroutine>) IN PROGRAM (<Program>) [<pass>] [IF FOUND].

PERFORM <index> OF <subroutine1> <subroutine2> <subroutine3> [<pass>].

Points to Note

Nested calls are allowed in subroutines (i.e. PERFORM within a FORM ...ENDFORM ).

Recursive calls are also possible.

To define local data, use the DATA statement after FORM . Each time you

enter the subroutine, the data is recreated (with an initial value) and released at the

end (from the stack).

To define global data used within a subroutine, use the LOCAL statement after

FORM . The values are saved when you enter the subroutine and then released at

the end (from the stack)

Function ModulesFunction Modules are general purpose ABAP/4 routines that anyone can use. Infact ,

there are a large number of standard function Modules available.

Function Modules are organized into Function Groups: Collections of logically related

functions. A Function module always belongs to a Function Group.

Syntax-



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FUNCTION <function module>

<Statements>

ENDFUNCTION.

Important information Associated with Function Module

Administration

Import/Changing/Export parameters.

Table Parameters/Exceptions.

Documentation

Source code - L<fgrp>U01 . <fgrp> is the Function Group

Global Data - L<fgrp>TOP .Global data for the function group- Accessible

across function modules in the function group.

Main Program - SAPL<fgrp> . Contains the list of all the include files for thatfunction group

Call a Function Module

To call a function module, use the CALL FUNCTION statement:

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CALL FUNCTION <module>

[EXPORTING f1 = a 1.... f n = a n]

[IMPORTING f1 = a 1.... f n = a n]

[CHANGING f1 = a 1.... f n = a n]

[TABLES f1 = a 1.... f n = a n]

[EXCEPTIONS e1 = r 1.... e n = r n [ERROR_MESSAGE = r E]

[OTHERS = ro]].

Function GroupsFunction groups are containers for function modules. Infact, there are a large number

of standard Function Groups. All of the function modules in a function group can

access the global data of the group.

Like executable programs (type 1) and module pools (type M), function groups can

contain screens, selection screens, and lists.

Points to Note

Function Groups cannot be executed.

The name of a function group can be up to 26 characters long.



When you create a function group or function module, the main program and

include programs are generated automatically.

Function groups encapsulate data.

How to create a Function Group

1. Goto Transaction SE80.

2. Select Program in the DropDown.

3. Write the name of the Function Group That you want to create. Generally User

made Function groups start with "Z". e.g. - <Z_FUNCTION_GROUP_NAME> .

Hit Enter Key.

4. Note that The TOP Include is create by default if the user checks the option of

creating a TOP include.

How to create a Function Module

1. Create a function Group (say " ZCAL").

2. Create a function module, set the attributes like (Function group, Application,

Short Text and Process Type) and Save.

3. Include file " LZCALU01" will have source code of first function module.

4.

Include file " LZCALTOP " will have global data.

5. Main program "SAPLZCAL" contains

o

Global data Include file " LZCALTOP "o Function modules include file " LZCALUXX "

o User defined Include files " LZCALF ..", " LZCALO.." and " LZCALI .."

6. Define interface parameters and Exceptions

7. Write the source code

8. Activate Function Module

9. Testing the Function Module - Single Test & Debugging

10. Documenting and Releasing a Function Module

1-introduction to abap

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