37719530 ABAP Programming Standards

8/8/2019 37719530 ABAP Programming Standards

1/33

ABAP Programming Standards - 4.XContents

Contents.............................................................................................................2Document Control Sheet.....................................................................................5Introduction.........................................................................................................6SAP Object Naming Conventions.........................................................................7

1. Programs, Functions, Includes and Reports...................................................72. Module Pools and Module Pool Includes........................................................83. Function groups.............................................................................................94. Function modules..........................................................................................95. Transaction Codes.......................................................................................106. Development Classes..................................................................................107. Logical Databases.......................................................................................108. Maintaining SAP Standard Objects..............................................................109. Data Dictionary...........................................................................................1110. Authorizations.............................................................................................1211. Profiles........................................................................................................13

Programming Standards...................................................................................151. One Command One Line:............................................................................152. Pretty Printer:..............................................................................................153. Variables.....................................................................................................164. Parameters ( P_ ).........................................................................................165. Parameter used as checkbox ( PX_ )and (RB_)for parameter used as radio-button

166. Select-options ( S_ ).....................................................................................167. Ranges ( R_ )...............................................................................................168. Constants (C_ )............................................................................................179. Counters ( N_).............................................................................................1710. Internal table (IT_) for Standard tables, (IS_) for Sorted tables, (IH_) for hash tables

1711. Structure ( X_ )............................................................................................1812. Flags ( FG_ )...............................................................................................1913. Error Messages............................................................................................1914. Subroutines.................................................................................................2015. Literal Text:.................................................................................................2116. PF-Status.....................................................................................................2217. External Files...............................................................................................2218. Variants.......................................................................................................2219. Messages....................................................................................................2320. Report Formatting.......................................................................................2321. Batch Data Input.........................................................................................2322. Authorization Checking...............................................................................2323. Lock objects................................................................................................2424. Debugging...................................................................................................24

Code Documentation........................................................................................25Optimization......................................................................................................27

1. Avoid Dead Code:........................................................................................272. Logical Database:........................................................................................273. Techniques for efficient Database selection................................................274. Internal Tables............................................................................................375. If Condition:.................................................................................................406. Case Statement:..........................................................................................407. ABAP Statements........................................................................................408. Describe Statement:....................................................................................419. Field Length:...............................................................................................4110. Arithmetic Operators...................................................................................4111. Use of tables...............................................................................................4112. WHERE clause.............................................................................................4113. Aggregate functions....................................................................................4114. Join..............................................................................................................42


2/33

15. Not Operator...............................................................................................4216. Minimizing the database load......................................................................4217. Standards for Specific Statements..............................................................4218. Coding Tips.................................................................................................42

ABAP Module Pool Standards and Practices......................................................431. Program Structure.......................................................................................432. Screen Definitions.......................................................................................433. GUI interfaces..............................................................................................434. POP-UP windows..........................................................................................43

5. OK_CODE (SY-UCOMM)................................................................................446. Update........................................................................................................44NULL VALUES....................................................................................................44INDEXES............................................................................................................45BUFFERS...........................................................................................................46ABAP Objects....................................................................................................48Appendix A : Table of Application Area Code....................................................53Appendix B : Standard Program Structure........................................................54Appendix C : Business Short, Medium, Long Names.........................................57Appendix D : Template Screen Flow Logic Structure........................................58

VersionDate of IssuePrepared byNameDesignation/Role-DepartmentEmail IDSignature

Reviewed byNameDesignation/RoleEmail IDSignature

Approved byNameDesignation/Role-DepartmentEmail IDSignature

Issued/ Base-lined byNameDesignation/Role-DepartmentEmail IDSignature

After completion of each review cycle, configuration manager must increment the version number.The document history is available with the Software Quality Assurance department.

Document HistoryVersion No.Date of IssueLocation of ChangeDescription of the Change

IntroductionThe ABAP language is an "event driven". The ABAP processor controls the execution of an event. For example, the

event AT-SELECTION-SCREEN is executed when the user hits ENTER on the selection screen and the event START-

OF-SELECTION is executed when the user presses PF13 to start the program. Because the ABAP languageincorporates many "event" keywords and these keywords need not be in any specific order in the code, it is wise to

implement in-house ABAP coding standards.

This document contains a list of possible ABAP coding standards, as well as some efficiency standards.Note: Customer supplied ABAP standards, if any, for a project takes precedence over this document. However, if there

are no coding standards supplied by the customer, Intelligroups standards shall be used for the project. Also, if any partof the document is not relevant to the project, considering the nature of the project, then all those sections relevant to the

project shall be adhered to. The programming standards being used shall be referred to in the project plan for the project.

SAP Object Naming ConventionsThis section defines the naming conventions for the following object types found in the SAP environment:

Programs, Functions, Includes, and Reports

Module Pools, Module Pool IncludesFunction Groups, Modules

Transaction Codes

Development Classes

Logical Databases

SAP Standard objects

Data Dictionary elements

Programs, Functions, Includes and ReportsThis section defines the naming conventions to be used by ABAP programs, functions, includes, and reports created in

the SAP system. Refer to Maintaining SAP Standard Objects (Section 2.1.7) if you are modifying a SAP standard object

Object names will consist of eight (8) characters formatted as follows:

Position Description

1 Usage: "Y" Tools and Utilities that are not to be migrated to production.


3/33

"Z" Application programs that will be moved to production.

2 SAP Application area (Ref. Appendix A)

4 -7 Type of program:

FUNC for function programs

"REPT" For Report programs, interactive report programs

BDCP for BDC programs BOLT for Bolt on Programs

SCRP for Script driver programs

INCL" For Include Module

MODP for Module pool programs

SUBP for Subroutine pools

INTP for Interface pools

CLSP for Class pools

9-27 should be a meaningful description for the program.

29-30 Reserved for future use/versions.Report and update program include object names will consist of eight (30) characters formatted as follows:

Position Description1 Z Required by SAP

2-7 Same as positions 4-7 in program name

9-23 Should be a meaningful description for the include

25-27 Usage:

"TOP" Data Declarations, Tables, etc.

PAI for PAI Modules

PBO for PBO modulesFnn; for Subroutines (Forms)Where "nn" is a numeric integer between 00 and 99.

The following is an example customer program for the application area M, and the appropriate includes:Program name ZM_REPT_DISPL_MATERIAL_LIST_01

Data include ZM_INCL_ MATERIAL_LIST_TOP_01

Form routine include ZM_INCL_ MATERIAL_LIST_F01_01

Module Pools and Module Pool IncludesThis section defines the naming conventions to be used for module pools and module pool includes created in the SAP

system. Module Pool names will consist of thirty (30) characters formatted as follows:


1-3 "SAP" - This is the SAP standard

4 Module pool type:"M" - Screen Module pool

"D" - Dialog Module pool

U" - Update Module pool

"F" - Subroutine Module pool

5 "Z" - Indicates a user defined module

6 Application Area (Ref. Appendix A)

7-27 User defined; should be meaningful for the application preferably the

Transaction codeModule Pool Include object names will consist of thirty (30) characters formatted as follows:


1 Module pool type:

"M" - Screen Module pool

"D" - Dialog Module pool"U" - Update Module pool

2-22 User defined; should be meaningful for the application preferably the

Transaction code

24-26 Usage:"TOP" Data Declarations, Tables, etc.

PBO; PBO modules

PAI; PAI modules

Fnn; Subroutines (Forms)

Where "nn" is a numeric integer between 00 and 99.

The following is an example customer module pool for the application area M, and the appropriate includes:

Program name SAPMZMZ_MAT_LIST


4/33

Data include MZ_MAT_LIST_TOP

Form routine include MZ_MAT_LIST_F01

PBO include MZ_MAT_LIST_PBO

PAI include MZ_MAT_LIST_PAI

Function groupsThis section defines the naming conventions to be used for function groups. Function group names of twenty six (26)

characters formatted as follows:


1 "Z".


User defined; should be meaningful for the function group

Function groups should contain related function modules and have the global interface flag turned off.Function modules

This section defines the naming conventions to be used for function modules. Function module names are recommended

to be very descriptive. The following is a suggested naming convention:


1 "Z" required by SAP


4-30 Use descriptive words, separated by underscores

Function modules should always reference data dictionary structures in the interfaces for export, import and tables. Thi

is mandatory if the function module being created is to be used for RFC interfaces.Transaction Codes

This section defines the naming conventions to be used for transaction codes (TCODE) created in the SAP system

Transaction code names will consist of Twenty (20) characters formatted as follows:

This section defines the naming conventions to be used for function groups. Function group names of twenty-six (26)



1 "Z".


4-20 User defined; should be meaningful for the function group

Development Classes.

This section defines the naming conventions to be used for development classes DEVC stored in the TDEVC tableDevelopment classes are used to pool related SAP objects into one common area for easier reference. Development class

names will consist of Thirty (30) characters formatted as follows:

This section defines the naming conventions to be used for function groups. Function group names of twenty six (26)



1 "Z".2 Application Area (Ref. Appendix A)

4-27 User defined; should be meaningful for the function group

Logical Databases.This section defines the naming conventions to be used for logical databases created for use with ABAP programs

Logical database names will consist of twenty (20) characters formatted as follows:

Position Description1 Usage:

"Y" Tools and Utilities that are not to be migrated to production.


2 Alphanumeric identifier (0 - 9, A - Z)


4 - 14 Meaningful Alphanumeric identifier

15 - 20 Reserve for future

Maintaining SAP Standard ObjectsThe purpose of this section is to define the naming conventions to be used whenever working with SAP standard objects

SAPS delivered objects are not to be modified. User exits should be used whenever possible or address modifications via


5/33

the customizing facilities provided.

If a SAP standard object is to be modified, the object(s) must be copied and renamed. The copied object can then be

maintained and substituted in the program path.

For functions, includes, and reports, the first position is to be changed to "Z". For Module Pools and Module Pool

Includes, change the 5th position to a "Z". The purpose of this procedure is to ensure that all SAP delivered code remain

intact as well as identifying all program customizations when migrating to a new release.

In the event ABAP programs, that the above is not possible, Include modules must be added to where the customizedcode must be called. The include module must indicate (in the documentation) its purpose and location where it is called

from.

Data DictionaryTransparent tables.Position Description

1 Y,Z or T9

2 Application identifier3 - 16 meaningful description

ViewsViews are virtual tables. The length of the view names can be sixteen (16) characters.


1 Y, Z or T9

2 Application identifier

4 - 8 VIEW9 - 16 meaningful name

StructuresThe following naming convention is to be used for structures, by position:


1 Z, Y, T9 required by SAP2 Application identifier

4 -10 STRUCT11 - 30 Meaningful description

Domains

Domains define the physical attributes of a field. Domains can be checked against value tables or be assigned a checktable depending on the usage for the domain. Domain names should be six (6) characters long and are to be defined by

the following naming standards by position:

Position Description1 Z & Y


4 - 7 DOM

8 - 30 Meaningful name

Example:

ZM_DOM_MATERIAL

Data ElementsData elements define the description for a field (Semantic domain). Data elements are to reference a corresponding

domain that matches the physical requirements for that element. Data element names should be six (6) characters long

and are defined by the following naming standards by position:


1 Z, Y or T9


4 - 7 DEL

8 - 30 Meaningful name

Example:ZM_DEL_MATERIAL

Fields


6/33

Fields are to be descriptive and should not exceed 6 characters. Long field names are cumbersome from a programming

perspective. It is recommended that the field name be named according to the associated data element in the following

convention.

However SAP allows up to 30 characters for field names.

AuthorizationsObject Class

An authorization object class, groups common check objects together in a logical group. Authorization class has a lengthof four (4) characters and should be defined as follows:

Position Description1 Z

2-4 3-character short business name

Check objects (Authorization Objects)Check objects are objects that are called from ABAP to check the login users authority to perform a function or check

access to specific field values.

Naming convention:Position Description

1 Z Required by SAP

2 Application area (Ref. Appendix A)

3 _ underscore

4-10 Use meaningful words

Application AreaAuthorizations control the values of a specific check object for which a user is to have access to. A value or range of

values is assigned to each field based on the authorization. The second character for any authorization must not be an

underscore _, this is reserved by SAP.

Naming convention, suggested for consistency with check objects:


1 Z Suggested by SAP


3 _ underscore4-10 Use meaningful words

Alternative naming convention (Release 2.2):

Position Description1 Application area (Ref. Appendix A)

2 : Colon

Use meaningful words

ProfilesProfiles link multiple authorizations into one common group, usually defined as a business profile. A business profile is

assigned specific authorizations to perform tasks related to the security level of that business profile. The second

character for any profile must not be an underscore _. This is reserved by SAP.

Naming convention, suggested for consistency with check objects:


1 Z as suggested by SAP


3 _ underscore4-10 Use meaningful words

Alternative naming convention (Release 2.2):



2 : colon

Use meaningful words

Programming StandardsOne Command One Line:

Each ABAP command consists of a sentence ending with a period. Multiple commands can be on one line; however, a

a standard start each new command on a new line. This will allow for easier deleting, commenting, and debugging.


7/33

Pretty Printer:The ABAP editor has a PP (Pretty Printer) command to indent by 2 positions specific lines of code and add subroutine

comments. Event keywords are typically not indented. This command is CPU intensive, therefore, do not overuse it.

TYPES: BEGIN OF IT_TAB,

F1 TYPE sg-field1,

F2 TYPE sg-field2,

END OF IT_TAB.

DATA: TAB TYPE STANDARD TABLE OF IT_TAB WITH HEADER LINE.

DATA: f1 TYPE I,f2 TYPE I.

START-OF-SELECTION.

IF f1 = f2.

f1 = 0.

ELSE.

f1 = 1.

ENDIF.

SELECT * FROM tabl

WHERE field1 EQ sg-field2

AND field2 BETWEEN sg-field5 AND sg-field6.MOVE ...

APPEND ...

ENDSELECT.

END-OF-SELECTION.

LOOP AT tab.AT NEW f1.

CASE F1.

WHEN ...WRITE:/ ...

WHEN ...

WRITE:/ ...

ENDCASE.

ENDAT.

WRITE:/ f1,

f2,

ENDLOOP.

VariablesABAP variable names can be up to 30 characters for DATA fields and subroutines and up to 8 characters for SELECT-

OPTIONS and PARAMETERS, therefore, as a standard make the names descriptive. Since SAP segment/table-field

names are hyphenated with a '-', use an '_' to hyphen program-specific variables. Whenever possible, TYPE paramete

should be used to define work fields.Ex. DATA: V_MATNR TYPE MARA-MATNR.

All program variables should use the following prefixes:

Parameters ( P_ )Parameters variable are used to allow data entry at the selection screen before program execution. These variables have a

limited length of eight (8) characters. Variable types of this category must be prefixed with P_. The following are

examples of variable names to be used.

PARAMETER: P_VKORG TYPE MVKE-VKORG,P_VTWEG TYPE MVKE-VTWEG.

Parameter used as checkbox ( PX_ )and (RB_)for parameter used as radio-button

Select-options ( S_ )The SELECT-OPTIONS for statement generates a program variable used for selection

criteria. This allows a user at the selection screen to enter in a range of values. The variable generated is actually a

system-generated table containing -high value, -low value, -sign, and -option

for the table field selected. Variable types of this category must be prefixed with S_ and have a limited length of eight

(8) characters. The following are examples of variable names to be used:DATA: V_MATNR TYPE MARA-MATNR.


8/33

SELECT-OPTIONS: S_MATNR FOR V_MATNR.

Ranges ( R_ )

The RANGES for statement generates a program variable used for selection criteria muchlike the SELECT-OPTIONS. The variable generated is actually a system-generated table containing -high

value, -low value, -sign, and -option for the table field selected. Variable types of this

category must be prefixed with R_ and have a limited length of thirty (30) characters. The following are examples of

variable names to be used:

DATA: V_MATNR TYPE MARA-MATNR.

RANGES: R_MATNR FOR V_MATNR.

Constants (C_ )

Constant variables do not change during the execution of a program. Whenever possible the literal itself should be used

These field types should be prefixed with C_. The following are examples of variable names to be used:

Example:

DATA: C_MATNR TYPE V_MATNR VALUE 000000000010000001,

C_TRUE VALUE 1,

C_FALSE VALUE 0.

Counters ( N_)A counter is a variable which is incremented once for each iteration.

Internal table (IT_) for Standard tables, (IS_) for Sorted tables, (IH_) for hash tablesTYPES TYPE|LIKE OF [WITH UNIQUE/NON-UNIQUE ]

[INITIAL SIZE ] {WITH HEADER LINE].

Types of tables:

1. Index Table - Standard Table and Sorted Table

2. Hashed table

Standard Table:

We can access records either using the table index or the key. If we use the key the response time is in linear relation to

the number of table entries. The key of a standard table is always NON-UNIQUE. Standard tables are generically index

tables.

Sorted table:

The entries are always saved and sorted according to the key. We can access records either using the table index or the

key. If we use the key, the response time is in logarithmic relation to the number of table entries since the system uses

binary search. The key of a standard table can be either UNIQUE or NON-UNIQUE. Sorted tables are generically index

tables.

Hashed table:

We can access hashed tables using their key only. The response time is constant and does not depend on the number of

the entries since the system uses a hash algorithm. The key of a standard table must always be UNIQUE.

Guidelines for using internal tables: -

We have to use WITH TABLE KEY when reading sorted and hashed tables otherwise the system may use wrong

procedure.

Do not fill sorted tables using index operations.

A sorted table cannot be resorted.

Hashed tables cannot use index operations.

Hashed table is used to store frequently read master data in an internal hashed table to avoid redundant database reads.Key access can be used with any table type.

We should never use the older techniques in the 4.X development

TYPES: BEGIN OF T_MARA,

MATNR TYPE MATNR,

MAKTX TYPE MAKTX,

WERKS TYPE WERKS_D,


9/33

END OF T_MARA.

DATA: IT_MARA TYPE STANDARD TABLE OF T_MARA WITH HEADER LINE.

DATA: BEGIN OF IT_INTTAB OCCURS 100,

FIELD1 LIKE SG-FIELD1,


DATA: END OF IT_INTTAB.

Dont use occurs 0 in the internal table declaration , if less than 8kb is stored in the internal table.

Use the approximate number of rows in the internal table declarationThe CLEAR should be used to initialize the table header record.

The REFRESH should be used to delete all table entries and release any paged out area. It is recommended tha

before a table is used; perform a REFRESH then a CLEAR in this order. A REFRESH does not clear the header record.

The FREE should be used at the end of the program in the wrap-up section. Performing a FREE will release

the storage area in the system roll area allotted to the table and deletes all lines.

Structure ( X_ )

Records or Structures consists of a fixed number of data objects (also called components of the record)

Example: DATA: BEGIN OF X_STRUCTURE,


FIELD2 LIKE SG-FIELD2.

FIELD1 TYPE SG-FIELD1,

FIELD2 TYPE SG-FIELD2.

INCLUDE STRUCTURE MARA.DATA: END OF X_STRUCTURE.DATA: X_MARA TYPE MARA.

Flags ( FG_ )Flags are variables that contain only one of two values. These variables will be defined as character of length 1. In allcases, the following values must be complied with:

Should be used for "NO"/ "FALSE"/"OFF"

X should be used for "YES"/"TRUE"/"ON"

These variables types are to be suffixed with FG_. The following are examples of variable names to be used:

Eg. W_EOF_FG TYPE C

W_CONTINUE_PROCESSING _FG TYPE C

Error MessagesThe purpose of this section is to define the naming conventions to be used for standard error messaging. Standard SAP

error messages should be used whenever possible to eliminate redundancy. If it is determined that additional error

messages are to be generated, assign them according to the guidelines described in this section. The following are the

three parameters to be defined in this section:

Message ID

Message SeverityMessage Number

Message IDsMessage IDs are twenty character names given to a group of related messages. The following are the naming standards

by position for message IDs:

1 "Z" Required by SAP2 Application area code (Ref. Appendix A)

2 - 20 Meaningful description

Message SeverityMessage severity defines the action performed upon execution of the message. The following are the allowable messageseverity codes:

A "Abend" - the transaction aborts and the user is unable to continue.

E "Error" - entered data is invalid. The user must modify or reenter the data.

W "Warning" - the program allows the user to override the particular warning and continue, or modify the data, which

caused the warning.

I "Information" - displays information that may be of interest to the user. The user must press enter to continue.

S "Success" - a success message is an informational message displayed on the next screen,

Such as "Transaction completed successfully".Message Number


10/33

Message numbers are the unique 3-character identifiers of a message. Message numbers range for 001 to 999. The next

available should be used.

SubroutinesIf a block of code is executed more than once, it should be placed in a subroutine at the bottom of the code. This makes

the code more readable, requires less indentation, and is easier to debug since the debugger can jump through an entire

subroutine via a PF key. The name of the subroutines should be descriptive and less than 30 characters.

Use local variables whenever possible within subroutines for modularization purposes. However, frequently used

subroutines within one program call should use global variables to eliminate creation time of those local variables.Prefix with L for the respective declarations.

It is recommended to pass data to and from subroutines using the USING statement in the perform. This does not apply

to field initialization subroutines and global subroutines.

Use of the CHANGING clause is up to programmer preference but is good for subroutine documentation.

Subroutines that are to be called by multiple programs should be created as a function module. External subroutines

should also be implemented as Function Modules.

Subroutine examples:

FORM CALCULATE_MATURITY_DATE.

MAT_DT = SY-DATUM + DAYS.

ENDFORM.Because of the added overhead of calling subroutines, functions, etc., you should avoid the following style of coding:

PERFORM SUB1.

FORM SUB1.

IF field NE 0.

..ENDIF.

ENDFORM.

Instead, code the following:

IF field NE 0.

PERFORM SUB1.

ENDIF.

FORM SUB1.

ENDFORM.All Subroutines (Forms) must be placed after the END-OF-SELECTION statement.

Order of forms should be the same as that of performs (not a hard and fast rule).Always have a type declaration for the formal parameters. If a particular parameter is likely to assume different types of

values use TYPE ANY.

There are several ways to assign type specifications to subroutine parameters:

FIELD2 LIKE BTABLE-FIELD2.

The type of the data object dbtable-field2 is used as the basis for type checking which then takes place as with TYPE.

FIELD3 TYPE C ... assigns to field3 the self-defined or predefined type C.

With the type specifications ANY, TABLE, C, N, P and X, typing of the formal parameter is generic.FIELD4 TYPE LINE OF ITABLE.

The type ITABLE must be an internal table. Field1 gets the line type of ITABLE. Type checking then takes place as with

TYPE. Typing of this kind is not allowed with TABLES parameters.

FIELD5 LIKE LINE OF ITABLE.

The line type of the internal table ITABLE is used as the basis for type checking which then takes place as with TYPE.Typing of this kind is not allowed with TABLES parameters.

If the actual parameter has a generic type, e.g. a generic formal parameter is passed to another typed formal parameter;complete type checking cannot be performed until runtime.

Incorrect type specifications then result in a runtime error.

Literal Text:

Literal text, which is printed on the report, should be handled in two ways.

One way is to hard code the literal in the code and give the option of maintaining Text Elements for multi-lingual clients

So, the following form of literal text should be used most of the time.

WRITE:/ 'Grand Total:'(001).

Another way is to always use Text Elements.


11/33

WRITE:/ TEXT-001.

The advantages to the first way are readability and the Text Element only needs to be maintained for multi-lingual

clients. The advantage to the second way is easier maintainability if TEXT-001 is coded several times in the program

and it needs to be changed.

PF-StatusPF Status is a custom status bar defined to be used by a screen or interactive program to enable user actions. The

standard SAP format must be used. The table below defines the usage of standard function keys. These function keys do

not have to be enabled but when used, must comply with the standards defined in this section. These function keys arenot to be replaced by user defined keys. The OKCODE is of length 10 characters.

PF Key OK-CODE Description

01 HELP Display help screen for current field

02 PICK Select entry (same as double-click).

03 BACK Exit current transaction. Overrides mandatory entries.

04 LIST List Possible Entries.

10 MENU Menu bar.

11 SAVE Save entries.

12 RW Cancel current request, Mandatory entries override.

13 PRI Print.14 DLT Delete.

15 EXIT Exit (Fast EXIT) leave transaction. Same as PF03.

21 P-- First page of document.

22 P- Previous page.

23 P+ Next page.24 P++ Last page of document.

External FilesExternal files are to be defined as logical files via the customization menu path. This allows for consistent naming of

files without having programs being dependent on the actual UNIX file name.For Presentation Server Upload/Download, use

GUI_UPLOAD instead of WS_UPLOAD and

GUI_DOWNLOAD instead of WS_DOWNLOAD.

VariantsVariants are program specific objects, which define, set parameter entries required at program execution time. Variant

names will consist of fourteen (14) characters formatted as follows:Position Description

1 Usage:

"Y" Tools and Utilities that are not to be migrated to production.


2 SAP Application area (Ref. Appendix A)

4-7 FUNC for function programs

"REPT" For Report programs, interactive report programs

BDCP for BDC programs

BOLT for Bolt on ProgramsSCRP for Script driver programs

INCL" For Include Module

MODP for Module pool programs

SUBP for Subroutine pools

INTP for Interface pools

CLSP for Class pools

8 Underscore "_"

9 "V" for variant.10-14 Meaningful information

MessagesAll Error messages are to be implemented via MESSAGE IDs (Ref. Section 2.5.1). Any text messages must use

NUMBERED-TEXT, defined via include text. The purpose of this is to make any output message text language

dependent.

Report Formatting


12/33

Blank lines are to be specified using SKIP as opposed to multiple WRITE / statements.

Use NUMBERED-TEXT for all screen text to be displayed. This is defined via include text and is language dependent.

Batch Data InputBatch data input sessions should be limited to approx. 250 transactions per BDC group. This number can vary greatly

depending on the quality of the data being processed. Large batch ABAP programs are to be avoided due to the single-threaded nature of the batch environment. These programs are to be broken up into smaller batch programs, where

appropriate.

Authorization CheckingAuthorization objects should be checked at the selection screen of report programs or at the transaction code level. All

check objects created must be documented thoroughly and given to the security administrator.

Lock objectsLock objects should be created as function modules (Enqueue / Dequeue) in a customer function group.

DebuggingAll debugging code must be removed from a program before migration to a controlled environment (i.e. Quality

Assurance, Production). This includes breakpoints and any code associated with testing.

ABAP code is fairly self-documenting. However, it is wise to provide future programmers with documentation. Explain the

purpose, design, structure and any testing hints at the top of the program. Maintain a history of modification notes, dated,

with the most recent change first. Comment work fields, and fields in work records especially those used for interfacing.

Comment all subroutines with their purpose. Comments should explain what the code is doing, not how the code is doing it.

Do HELP EDITOR and read the documentation on the IC command.

For Report Headers: -

Refer Appendix B.

For documenting Changes within a program:-

*-------------------------------------------------------------------------------** Begin of Change as part of # Request | User Name |On

*-------------------------------------------------------------------------------*

*-------------------------------------------------------------------------------** End of Change as part of # Request | User Name *

*-------------------------------------------------------------------------------*

For declarations:-

Database Tables:-Description of the table should be documented against the table name

*----------------------------------------------------------------------*

* Declaration for Tables

*----------------------------------------------------------------------*

Global variables:-Short description of the variable should be documented against the variable name

*----------------------------------------------------------------------** Declaration for Variables

*----------------------------------------------------------------------*

Constants:-

Short description of the constant should be documented against the constant name

*----------------------------------------------------------------------*

* Declaration for Constants

*----------------------------------------------------------------------*

Flags:-


13/33

Short description of the flag should be documented against the flag name

*----------------------------------------------------------------------*

* Declaration for Flags

*----------------------------------------------------------------------*

Internal tables:-

Short description for the use of internal should be documented against the internal table name*----------------------------------------------------------------------*

* Declaration for Internal tables

*----------------------------------------------------------------------*

Events:-

Should be of the type given below

Start of Selection:-

*----------------------------------------------------------------------** Start of Selection

*----------------------------------------------------------------------*

Subroutines:-

*&---------------------------------------------------------------------*

*& Form test_ for_ material_ type

*&---------------------------------------------------------------------*

* Description

*----------------------------------------------------------------------** --> Formal parameter type and description*----------------------------------------------------------------------*

Avoid Dead Code:Avoid leaving "dead code" in the program. Remove defined fields, which are never referenced, and code, which can

never be logically executed. Always perform Extended Program Check (EPC) before delivering the object. The path for

EPC is ABAP editor -> Program -> Check -> Extended Program Check.

Logical Database:Choose the most efficient logical database possible. Study the selection criteria and which secondary indexes are used

for that view. Provide the appropriate selection criteria to limit the number of database read. Force users to provide

selection criteria by evaluating the selection criteria entered on the selection screen during the AT SELECTIONSCREEN event. Remember the power of match codes / Search Helpsfor selection and report sorting. Always use GET

statement to retrieve the required fields.

Use the new features as of release 4.x as mentioned below:-

Basic form NODES node.

Additions:1.... TYPE type.

There are four different types of nodes in a logical database:

(Refer to help on LDB for further details)

Use LDB_PROCESS function module as of release 4.6 to call LDBs without having to change roll areas. (Refer to

Function module documentation on LDB_PROCESS for further details)

Adjustment to the Function Builder: The program structure created and the logical database builder have both been

modified to forms recognized by the function builder.

Techniques for efficient Database selectionThe following basic guidelines need to be considered while retrieving data from the database:

Avoid unnecessary database accesses

Keep the number of data records small

Reduce information transfer to application server

Reduce the load on the database engine

Use database locks and SAP Enqueue


14/33

A detailed explanation for each of these rules is as under.

Reduce Information transfer to Application server.

Specify the individual column (field) names of the data you want to retrieve in the select statement

E.g. SELECT single MATNR ERSDA

INTO (V_MATNR, V_ERSDA)

FROM MARAWHERE MATNR EQ 000101234567890123.

In this example, only 2 fields are transported back to the work area for each matching record. This greatly reduces the

amount of data transfer (network traffic) - especially for tables, which have a large number of fields/large record size.

Our objective is to reduce network traffic as much as possible and for this reason, ABAP provides several Aggregate

functions, which are part of the SELECT, statement. By using these, the DBMS makes the computations instead of

transferring all the data to the application.

e.g.1 Use: SELECT COUNT(*)FROM MARC

WHERE MATNR EQ 000101234567890123.

SY-DBCNT will hold the number of matching records found.

Instead of: SELECT * FROM MARC

WHERE MATNR EQ 000101234567890123.

ADD 1 TO V_COUNT.

ENDSELECT.

e.g.2 Use: SELECT SUM( TRAME )

INTO V_TOTAL_IN_TRANS

FROM MARC

WHERE MATNR EQ 000101234567890123.

Instead of: SELECT * FROM MARC

WHERE MATNR EQ 000101234567890123.V_TOTAL_IN_TRANS = V_TOTAL_IN_TRANS + MARC-TRAME.

ENDSELECT.

Use update statement sparingly. Only update the columns, which are changed, and do not overwrite the entire line

While using SELECT SINGLE

SELECT SINGLE is used instead of SELECT-ENDSELECT loop if full primary key is known. Otherwise, use

SELECTup to 1 Rows. SELECT SINGLE requires one communication with the database system.

Ex. Use SELECT SINGLE * FROM SCARR WHERE CARRID = 'LH'.

Instead of SELECT * FROM SCARR

WHERE CARRID = 'LH'.

ENDSELECT.

Keep the number of data records small.

Never use Nested SELECT loops. Instead consider options: Views, Joins or select statement with for ALL ENTRIES

OPTION

Always use the WHERE clause in the corresponding SQL statement. An Application should read only those lines o

the table that are necessary for the processing. Therefore formulate filter condition not through CHECK statements

rather through part of WHERE statements

E.g. Always use option 1 instead of option 2.

Option 1

E.g. SELECT MATNR


15/33

INTO TABLE IT_MARA

FROM MARA

WHERE MATNR LIKE 23%.

Option 2

E.g. SELECT MATNR

INTO MARA-MATNRFROM MARA.

CHECK MARA-MATNR+0(2) NE 23.

MOVE MARA-MATNR TO IT_MARA-MATNR.

APPEND IT_MARA.

CLEAR IT_MARA.

ENDSELECT.

Use the indexes of the relevant database tables to make your WHERE clause more efficient, by checking all index fields

for equality (EQ, =) and using the AND operator. The primary key of a database table is automatically its primary index

You can also create secondary indexes for a database table in the ABAP Dictionary. However, certain considerations

need to be made while creating secondary indexes.

The success with which an index supports data selection from a table is dependent on how closely the dataset selected

using the index represents the dataset finally to be selected. This can be best illustrated by means of an example.

An index to the table EXTAB containing the fields FIELD1, FIELD2, FIELD3 and FIELD4 in this sequence is to be

defined. The table is to be accessed using the SELECT statement:

SELECT *

FROM BSPTAB

WHERE FIELD1 = X1 AND

FIELD2 = X2 AND

FIELD4 = X4

Since FIELD3 is not specified more precisely, sorting of the index functions only up to FIELD2. If the database system

accesses the data using this index, it will quickly be able to access all records for which FIELD1 = X1 and FIELD2 = X2

are valid. It will then have to select all the records for which FIELD4 = X4 from this set.

Some Guidelines while creating Indexes

The speed of access provided by this index is heavily dependent on how closely the dataset selected via the indexcorresponds to the dataset to be finally selected.

Consequently, the sequence of the fields in the index is decisive in determining the speed with which data records are

accessed.

Fields, which frequently contains constants in many selections, should be located at the beginning. An index assistsselection only up until the first unspecified field. Fields should be included in an index only if they significantly restric

the set of data selected.

E.g.: The following selection is often made from an address file ADRTAB:

SELECT * FROM ADRTAB WHERE TITLE = 'Prof.' AND NAME = X AND FIRSTNAME = Y In an index

containing the fields NAME, FIRSTNAME and TITLE, the field TITLE would rarely narrow down further the records

specified via name and first name. It would not be useful, therefore, to include this field in such an index. An index

containing only the field TITLE might be useful, for example, if it is often necessary to select all the professors.

If selections are frequently made involving attributes that are not contained in the primary index, you should define

secondary indexes.

Please note that any additional indexes you create may place an additional load on the system, since they have to be

adjusted each time a change is made to the table contents. Every additional index therefore slows down the insertion of

records in the table. Tables in which entries are frequently written should generally therefore have only a few indexes.

Even if a suitable index exists for a selection, it may not always be used. The index selected depends on the database

system optimizer in use. You should usually therefore check whether an index is in use (see How do you check whether

an index is used? ).


16/33

The indexes for a table should therefore be as distinct as possible - that is, they should have as few fields in common as

possible. If two indexes for a table have many fields in common, this can complicate the choice of the most selective

index by the optimizer.

Define a database view via the ABAP Dictionary, which identifies the tables and fields that you are interested in. Then

SELECT from the view rather than the database table(s).

E.g. SELECT *

FROM Z_M_MARCWHERE MATNR EQ 000101234567890123.

This is preferable if multiple programs require the same data from the same table(s). If the set of data in these programs

requires changes, then the developer need only change the definition of the database view, rather than modify every

SELECT statement - i.e. greater reusability and maintainability.

If possible, avoid using the NOT operator in the WHERE clause, because it is not supported by database indexes; Inver

the logical expression instead.

Avoid using complex WHERE clauses since the system has to break them down into several individual statements for

the database system

If all you are interested in is retrieving all possible values for a given table field (i.e. you do not want duplicates), then

SELECT DISTINCT will provide that capability and will also restrict the amount of data passed back to the application

to only the set of unique values.

E.g. SELECT DISTINCT WERKS INTO V_PLANT FROM MARC.

ENDSELECT.

In this example, a value will be returned for each unique value of the field WERKS (Plant). If there are 3 unique plants

in table MARC, will be performed 3 times only, with each value of WERKS being placed into the work

area V_PLANT for each iteration. Each plant may, in reality, be present on multiple records, but this method returns

only unique values.

Be careful while restricting data on NULL values.

You will not find a record in a database table, if field has a Null Value and you are using the

Following WHERE-clauses:WHERE FIELDN = 0.

WHERE NOT fieldn = 0.

WHERE fieldn < 5.

WHERE fieldn > 5.

WHERE fieldn = SPACE.

WHERE fieldn SPACE.

If you want to read records with Null Values, you have to use IS NULL with your WHERE-clause:WHERE fieldn = 0 OR fieldn IS NULL.

WHERE fieldn < 5 OR fieldn IS NULL.

WHERE fieldn = SPACE OR fieldn IS NULL.

Where possible, avoid accessing the same data more than once (for example, by using SELECT before an UPDATE or

DELETE statement).

Reduce the load on the database engine

Use the 'into' syntax and push data directly into internal tables rather than using the row by row 'append' approach

Again this is an example of thinking in terms of 'sets' rather than 'rows'. Old-fashioned databases only knew about rows

Modern relational databases work better when dealing with sets of data. Try to work always in sets.

The order of the fields in the where clause of the select must be in the same order as the order in the Index. (Oracle

limitation but routinely should be used against all databases).

The addition INTO CORRESPONDING FIELDS in the INTO clause of the SELECT Statement is only effective for

large amounts of data, because the time required to compare the field names is otherwise too great.


17/33

There are two ways to get ordered data. The data can be selected using the addition ORDER BY from the database. Thi

is advisable for large amounts of data (> 10 MB) because the database system is the only component in R/3 with large

resources. Ensure that the ORDER BY can use an index. When a small amount of data is to be sorted, it can be done

with ABAP statement SORT.

Exactly the same is also valid for the usage of DISTINCT vs. DELETE ADJACENT.

Avoid unnecessary database accesses

Dont use identical select statements.

Use option 1 instead of option 2.

Option 1

e.g. To get Material DescriptionsLOOP AT IT_VBAP.

READ TABLE IT_MAKT KEY MATNR = IT_VBAP-MATNR TRANSPORTING MAKTXIF SY-SUBRC NE 0.

SELECT MATNR MAKTX APPENDING TABLE IT_MAKT-MAKTX WHERE MATNR

EQ IT_VBAP-MATNR.

ENDIF.

MOVE: IT_MAKT-MAKTX TO IT_VBAP-MAKTX.

ENDLOOP.

Option 2e.g. To get Material Descriptions

LOOP AT IT_VBAP.

SELECT SINGLE MAKTX INTO IT_VBAP-MAKTX WHERE MATNR EQ IT_VBAP-MATNR.

ENDLOOP.

Using Database Buffering

Saving database tables in local buffers can save a considerable amount of time. Wherever possible, use buffered data

and only use the BYPASSING BUFFER addition where absolutely necessary.

Note that the following additions automatically bypass the buffer:

SELECT ... BYPASSING BUFFERAny SELECT from a view (except a projection view)

SELECT FOR UPDATE...

Any aggregate function (COUNT, MIN, MAX, SUM, AVG)

Example: SELECT MIN (field1) FROM dbtable1 WHERE...

SELECT DISTINCT...

WHERE-clause contains ... IS (NOT) NULL

ORDER BY (other than PRIMARY KEY)

Any Native SQL statement

Joins.

An INNER join is a join where you expect that there will always be a relationship between all of the tables in the set, andif any of the relationships are missing, then you do not want to get the row.

Eg.

Consider 3 imaginary tables.Customer

MANDT (Primary Key)

CUST_CODE. (Primary Key)

Invoice

MANDT (Primary key)

INV_NUM (Primary key)

CUST_CODE (Foreign key to Customer)

Invoice_line


18/33

MANDT (PK)

INV_NUM (PK)

INV_LINE_NUM (PK)

You could construct an INNER join over these tables as follows

Customer Invoice Invoice_line

MANDT MANDT MANDT

inv_num === inv_numcust_code === cust_code

Say you then have to report off this information.

Your report would contain ONLY those customers which had Invoices which had at least one line. Customers without

invoices would not be included. Customers that had invoices but without a line would not be included.

This is the principle of the INNER join. All the data has to be there and be related.

Database views support ONLY the inner join concept.

Outer Joins

In the majority of cases inner joins will actually be the requirement, but in the minority of cases you will want to use an

outer join. Outer joins are useful where you may need all records from a certain table, that meet the selection criteria, and

all data from another table(s), IF it exists. But if the latter data does not exist, you still want to get the first table data.

Using our imaginary tables again.Suppose the requirement is not for an invoice report, but for a customer report, showing outstanding invoices. You want

to see ALL customers, so you can't use an inner join

(Incidentally therefore you can't use a database view, database views only support INNER joins) because if you did, you

would not see customers that had no invoices. So you would construct an outer join relationship as under:


MANDT MANDT MANDT

inv_num === inv_numcust_code ----> cust_code

In this situation you would get all customers regardless, and their invoices. You would only see the invoices, which had

at least one line as the join between invoice and invoice_line is still an inner join. If you wanted to be absolutely sure you

could code a double outer join as under:


MANDT MANDT MANDT

inv_num ----> inv_num

cust_code ----> cust_code

In this situation you would see all the invoices, even if they had no lines.

In reality in the above situation you would seldom code such a well defined relationship as invoice - invoice_line using

an outer join. If an invoice doesn't have a line then it is usually corrupt data.

Guidelines for using Joins

Using outer joins places a heavy load on the database engine (although no heavier that if you coded a nested select), so

be very parsimonious about the use of outer joins.

The performance of the join depends on the database optimizer used especially if there are more than two tables used for

joins.

Try to give maximum number of conditions in the ON clause. This is because the ON conditions are evaluated first and

the virtual table created as a result is the one on which the WHERE clause applies.

To process a join, use a view wherever possible instead of nested SELECT statements.

Using nested selects is a technique with low performance. The inner select statement is executed several times, which


19/33

might be an overhead. In addition, fewer data must be transferred if another technique would be used eg. Join

implemented as a view in ABAP Repository.

Use sub queries if possible. However, be careful while choosing the type of sub query to be written.

Example

Selects the flights for which at least one booking exists:

TABLES SFLIGHT.

SELECT * FROM SFLIGHT AS FWHERE EXIST

( SELECT * FROM SBOOK

WHERE CARRID = F~CARRID

AND CONNID = F~CONNID

AND FLDATE = F~FLDATE ) .

WRITE: / SFLIGHT-CARRID, SFLIGHT-CONNID, SFLIGHT-FLDATE.

ENDSELECT.

This is most assuredly not a Good Thing. What this is actually doing is forcing the database to do a separate selection

from SBOOK for each row in SFLIGHT. For a small number of records this would probably work OK - but once again

- on larger datasets it would hang. For every record in SFLIGHT a separate database operation is occurring in SBOOK

You might as well have coded the selections inside a loop.

This query is better written as follows;Select distinct F~*

into table IT_SFLIGHT

From SFLIGHT as F

INNER JOIN SBOOK as s on

S~CARRID = F~CARRID AND

S~CONNID = F~CONNID AND

S~FLDATE = F~FLDATE.

Following the above guidelines does not guarantee the most optimal selection from the database. Ultimately, it dependson the nature of the data and other associated factors.

Hence, it becomes mandatory to analyze the Selection from the database with the help of SQL Trace Tool. The following

features need to be checked in ST05:

a. Explain SQL.b. Identical select

c. Check summary

SQL Tuning Checklist

Consolidated selections

No row by row processing

No check statements

No selections within loops

Selections are 'into' internal tables - no appends

SQL trace check completedAll programs checked to make sure that they are using the full index and in the

Correct order.

Minimum or zero number of identical selects.

Use of appropriate Indexes

Internal TablesThe following are the guidelines for working with the Internal Tables:

Always use the READ statement with the Index or BINARY SEARCH.

Always read the required fields using TRANSPORTING f1 f2

Avoid nested looping on the internal tables.

Use EXIT statement to jump out of the loop, when the complete processing is done.


20/33

As far as possible avoid using Modify, Insert, Update, Append or Delete within the loop endloop.

For e.g.

Looping at ITAB:

INSERT INTO dbtable VALUES itable. NOT Preferred

ENDLOOP.

INSERT dbtable FROM TABLE itable

ACCEPTING DUPLICATE KEYS.IF NOT SY-SUBRC IS INITIAL.

... error handling

ENDIF.

When multiple records are to be inserted into a table, then use the second form as shown above rather than loop into the

internal table and inserting/updating single records.

INITIAL SIZE

This size does not belong to the data type of the internal table, and does not affect the type check. You can use the above

addition to reserve memory space for table lines when you declare the table object.

When this initial area is full, the system makes twice as much extra space available up to a limit of 8KB. Further memoryareas of 12KB each are then allocated.

You can usually leave it to the system to work out the initial memory requirement. The first time you fill the table, little

memory is used. The space occupied, depending on the line width, is 16


21/33

There are less than 100 rows

Rows are already in sorted order

If an internal table must be sorted and the above cannot be satisfied, fill the table in unsorted order and then sort

specifying key fields. To remove duplicates, if required, collect the rows from the sorted table into an auxiliary table.

Use APPEND LINES OF [FROM ] [TO ] TO

When appending fixed lines from an internal table to a new internal table.

MOVEAvoid unnecessary Moves by using the explicit work area operations:

APPEND workarea TO itable

INSERT workarea INTO itable

COLLECT workarea INTO itable

MODIFY itable FROM workarea

READ TABLE itable INTO workarea

LOOP AT itable INTO workarea

Move Command:When records a and b have the exact same structure, it is more efficient to MOVE a TO b than to MOVE

CORRESPONDING a TO b, if records a and b have the exact same structure.

MOVE BSEG TO *BSEG. is better thanMOVE-CORRESPONDING BSEG TO *BSEG.

Note: avoid unnecessary MOVEs by using explicit work area operations.

DELETE

Where appropriate.

With the new DELETE variant DELETE itable [FROM ...] [TO ...] WHERE ... the task of deleting a set of lines can be

transferred to the kernel.

If possible, WHERE should be used together with FROM... and/or TO... to enhance performance.

The performance gain when using

DELETE itable WHERE....

instead of

LOOP AT table WHERE ...

DELETE itable.

ENDLOOP.increases with the number of entries the internal table contains and the number of lines to be deleted.

When deleting adjacent duplicates use COMPARING fields as far as possible.

e.g. DELETE ADJACENT DUPLICATE ENTRIES from COMPARING F1 F2 If Condition:

When coding IF tests, nest the testing conditions so that the outer conditions are those, which are most frequently true

This will ensure minimal code execution. Similarly, for logical expressions with AND, place the most likely false firsand for the OR, place the most likely true first.

Case Statement:When testing fields "equal to" something, one can use either the nested IF or the CASE statement. The CASE is bette

for two reasons. It is easier to read and after about five nested IFs the performance of the CASE is more efficient.Note: CASE statement used in place of IF where field checked for > 2 values.

ABAP StatementsThe following should be avoided in the ABAP statements to improve efficiency:

Type conversions: The processor takes additional time to convert from one data type to another.

Type P fields: Unless rounding errors are not avoidable, do not use packed data variables.Nested Loops: Unless unavoidable, do not use nested loops. They eat up processor time.

If nested loops are unavoidable then

Avoid the following


22/33

SORT: I_VBAK by VBELN, I_VBAP by VBELN.

Loop at I_VBAK

Loop at I_VBAP where VBELN = I_VBAK-VBELN.

.

Endloop.

Endloop..

Instead use

SORT: I_VBAK by VBELN, I_VBAP by VBELN.

Loop at I_VBAK

Read table I_VBAK with key VBELN = I_VBAK-VBELN binary search transporting no fields.

Loop at I_VBAP from sy-tabix.

If I_VBAP-VBELN I_VBAK-VBELN.

Exit.Endif.

Endloop.Endloop.

Describe Statement:DESCRIBE TABLE [LINES ] [OCCURS ] [KIND ]To find out how many entries are in an internal table use DESCRIBE.

DESCRIBE TABLE ITAB LINES CNTLNS. is more efficient than

LOOP AT ITAB.CNTLNS = CNTLNS + 1.

ENDLOOP.

Field Length:To find out the length of a field use the string length function.

FLDLEN = STRLEN (FLD). is more efficient than

IF FLD CP * #.

ENDIF.

FLDLEN = SY-FDPOS.

Arithmetic OperatorsUse symbols for arithmetic operators instead of characters for better performance.Example: use instead of NE .

Use of tablesInternal tables vs field groups:

Using internal tables is more efficient than field groups and should be used when possible.

If the volume of data is very much, field groups are more efficient compared to internal tables in terms of memory

management.

WHERE clauseAlways try to use the columns which are used in indexes in SELECT statements WHERE clause along with other non-

indexed columns in the WHERE clause.

Aggregate functionsUse of aggregate functions in the SELECT expression list to find the minimum, maximum, count and average list instead

of computing it yourself.

JoinTo process a join, i.e. process data from 2 or more tables use view instead of nested select statements.

Not OperatorThe NOT operator cannot be used in an indexed access. Still it could be specified to avoid unproductive data transfer

between the database and the application.


23/33

Minimizing the database loadDo not use a SELECT statement to confirm existence before UPDATE or DELETE is used. Directly use UPDATE or

DELETE and then check the result with SY-SUBRC.

When large amounts of ordered data is to be read from the database, use the ORDER BY clause. (If the index exists, le

the statement use it.) If only a small amount of data is to be needed, then use the ABAP SORT.

The same logic applies to DISTINCT and DELETE ADJACENT.

Logical databases should be used whenever available for reports.

Standards for Specific StatementsASSIGN

Use of field symbols is discouraged unless necessity dictates. Field symbols, when used, should be documented in

program comments when defined and whenever used. Always have a type declaration for field symbols.

AT PFnnUse the AT USER COMMAND instead of AT Pfnn. This ensures proper response to the user command and is more

legible.CHECK

Use check statements whenever possible instead of nested IFs.User Interface (GUI)

GUI statuses should be used for interactive report programs and online programs. Use menu bar linking whenever

possible to build consistent GUI statuses for screens within a module pool.

CHECK, EXIT, REJECT, STOP & CONTINUE

Use these statements to suspend processing and/or skip remaining unnecessary processing for improved performance.

Coding TipsA program should test the system return code field (SY-SUBRC) after any statements that could potentially change its

value unless the outcome of the statement is not important for subsequent processing. The return code should always be

checked after any database table read/update statements.

LOOP . WHERE is faster than LOOP/CHECK because LOOP . WHERE evaluates the

specific condition internally.Ex. Use

LOOP AT ITAB WHERE NAME1 = KVAL..ENDLOOP.

Instead ofLOOP AT ITAB.

CHECK ITAB-NAME1 = KVAL.ENDLOOP.

ABAP Module Pool Standards and PracticesThe purpose of this section is to define the basic standards that all developed programs must comply with when creating

or maintaining Module Pools in the SAP environment. This section describes the rules surrounding the use of ABAPfeatures and components specific to Module Pool program types. Coding in the main program must comply with

standards and practices defined for ABAP (Section 4.0).Program Structure

The ABAP Programmers Workbench (SE80) should be used to create and maintain all Module Pool programs. A sample

flow-logic and associated modules for all screens in a module pool is defined in Appendix D.Screen Definitions

Screens are to use data dictionary fields for all variables. This does not include multiple selections like radio buttons.

Screens are to be numbered with an entry screen of 100. Reuse screens whenever possible.Tab Strips:

Use Tab strips wherever possible as they provide an easy way to define different application components on the same

screen and switch between them. Their intuitive design also makes them easier for the end users.GUI interfaces

GUI interfaces must follow SAP standards. User defined menus are to contain all actions that are applicable to the

transaction. Items that are not effective during a screen process are to be disabled. Commonly used selections are toappear as push buttons below the menu bar.

POP-UP windowsPop-up windows are allowed and to be used at programmer or customer preference. Programmatic circumvention of

pop-up windows must be included for batch data processing considerations.OK_CODE (SY-UCOMM)

An OK_CODE variable must be specified in all screens. This variable is defined via the field list of each screen created


24/33

(Exists as the last field in the field l).Update

Never use single-line Updates.

When the fields selected are part of the key, then to avoid multiple selections, use DISTINCT clause:

This clause should be used when there is a large amount of data, which cannot be handled in the memory, and when

there is an Index.

When the data is small and there is no Index, then use DELETE ADJACENT DUPLICATES.

A Null Value is an undefined value of a field in a database table.

Outputs a Null Value:After an ADD FIELD field n in the database table. All existing entries get a Null Value for field n.

After INSERT with a database view for the fields which are not defined in the view.

When reading a field with a Null Value from the database, the result will be:

SPACE for fields with type CHAR, RAW, LANG

0 for fields with type INT4, FLTP, DECEXESThe use of indexes for the database access can vastly improve the performance of reports.

Secondary index should be created when:

you select with fields without index support

you select only a small part of the table (< 5 %)

your WHERE-clause is easy (uses only ANDs) you often have to do sorts without index support

ABAP dictionary allows 16 secondary indexes for each table. But be very careful. Inserting and

Updating records will take longer and gives the database optimizer more choices to cause faults.

Secondary Indexes

Rules to follow when creating secondary index:

An index must be selective. An index is worthless, if you still get thousands of records.

Dont use too many fields. Most database systems use only a certain number of index

fields.

Use the most selective fields first.

Create the index for the main case. Be aware that other SELECTs can cause problems.

R/3 buffers are local to the application server and hold primarily run-time data.

Buffer types:

Table buffers for resident, generic and partially buffered tablesNumber range buffer

PXA Program buffer for ABAP loads

Presentation buffer for dynpros

CUA buffer for menu objects

Nametag buffer for ABAP dictionary information (table structures)

There are three basic buffering types:

Resident buffering (100%): the contents of the whole table are loaded into the buffer on the first access to any data from

the table.

Generic buffering a generic key (first n key fields) is specified when maintaining the technical settings. This generic key

divides the contents of the table into so-called generic areas. When accessing any data with a specified generic key, the

whole generic area is loaded into the buffer. The figure shows the case of generic buffering with one and two fields asgeneric key. A typical case of generic buffering is the client-dependent buffering (client is the first key field). When

specifying resident buffering for a client-dependent table, the ABAP Dictionary automatically uses generic buffering

with one key field.

Partial buffering (single record): only single records are read from database and stored into the buffer.

SQL statements bypassing bufferAll buffer types:

SELECT ... BYPASSING BUFFER

Any SELECT from a view (except a projection view)SELECT FOR UPDATE...

Any aggregate function (COUNT, MIN, MAX, SUM, AVG)


25/33

Example: SELECT MIN (field1) FROM dbtable1 WHERE ...

SELECT DISTINCT...

WHERE-clause contains ... IS (NOT) NULL

ORDER BY (other than PRIMARY KEY)

Any Native SQL statement

There are several statements, which cannot be satisfied from the buffer. These statements bypass the buffer and are sent

directly to the database. The above shows the statements that bypass any buffer type.

These statements should be avoided when programming with buffered tables in order to guarantee good performance. Anexception is the maintenance transactions on buffered tables.

These should use an explicit SELECT... BYPASSING BUFFER to ensure the most-up-to-date data directly from the

database.

R/3 Buffers - Possible Usage:

A productive system rarely changing data:

Table buffers for tables with:

Rather small size

('small' depends on access frequency)

Read-mostly access

E.g. control tables, customizing tables,

'small' master data

Special buffer for runtime objects: programs, dynpros, table structures

Buffering can be done only if there are no indexes:

A full table scan in buffer can be worse than a select with index from the database

ABAP Objects is a new concept in R/3 Release 4.0. The term has two meanings. On the one hand, it stands for the entireABAP runtime environment. On the other hand, it represents the object-oriented extension of the ABAP language.

This documentation introduces a selection of terms that are used universally in object orientation and also occur in

ABAP Objects.

Classes

Classes consist of ABAP source code, enclosed in the ABAP statements CLASS... ENDCLASS. For a local class, youenter this source code directly in the corresponding ABAP program. For a global class, it is generated by the Class

Builder in special tables within the R/3 Repository.

A complete class definition consists of a declaration part and, if required, an implementation part. The declaration part of

a class is a statement block:

CLASSDEFINITION.

...

ENDCLASS.

It contains the declaration for all class components (attributes, methods, events). When you define local classes, the

declaration part belongs to the global program data. You should therefore place it at the beginning of the program.If you declare methods in the declaration part of a class, you must also write an implementation part for it. This consist

of a further statement block:

CLASS IMPLEMENTATION.

...

ENDCLASS.

You can divide the declaration part of a class into up to three visibility areas:

CLASS DEFINITION.

PUBLIC SECTION.

...


26/33

PROTECTED SECTION.

...

PRIVATE SECTION....

ENDCLASS.

(For further details refer help on defining classes.)

CLASS-DATA ( a).

Declares static attributes in a class or an interface in ABAP Objects.

CLASS-METHODS meth.

CLASS-METHODS meth FOR EVENT evt OF cif.

Declares static methods in a class or interface in ABAP Objects.CLASS-EVENTS evt.

Declares static events in a class or interface in ABAP Objects.CLASS-POOL.

Additions:1. ... MESSAGE-ID mid

Introductory statement for a class pool. Class pools are programs with type Class Pool that serve as containers for globa

classes. You cannot enter the CLASS-POOL statement in a program yourself. Instead, it is generated by the Class

Builder.

Reference Variables

Objects are runtime instances of classes in the memory area of a program. A program accesses individual objects usingpointers called reference variables.

You declare reference variables using the statement

DATA TYPE REF TO .

Object Instances

Once you have declared an object variable for a class , you can create an object using the statement

CREATE OBJECT .To access the object components using the object variable , use the following syntax:

To access an object attribute : < obj>->To call a method : CALL METHOD < obj>->

Defining Interfaces

You can define interfaces in a similar way to classes; either locally in your program, or globally using the Class Builder

The definition of an interface consists only of a declaration part:

INTERFACE ....ENDINTERFACE.Incorrect syntax in ABAP Objects

(for details refer to help on Changes in release 4.6 - ABAP Objects - Replacement of Obsolete Statements for 4.6 )

BIT - Operations:-

The bit expression bitexp is calculated and the result placed in field x.You can use the four bit operators BIT-NOT, BIT-AND, BIT-XOR and BIT-OR. The operands are linked according to

the table below.

The priority is normal: BIT-NOT has priority over BIT-AND, followed by BIT-XOR, and then BIT-OR. You can use

any number of parentheses.

x y BIT-NOT x x BIT-AND y x BIT-XOR y x BIT-OR y

0 0 1 0 0 0

0 1 1 0 1 1

1 0 0 0 1 1

1 1 0 1 0 1


27/33

CATCH

Variants:

1. CATCH SYSTEM-EXCEPTIONS except1 = rc1 ... exceptn = rcn.

You can catch ABAP runtime errors in the processing blockenclosed in the CATCH ... ENDCATCH statements.

Note the following:

- rc1 ... rcn must be numeric literals.- CATCH ... ENDCATCH may be placed anywhere where

IF ... ENDIF (for example) may occur. It is local, not

cross-event.

- It may be nested to any depth.

- It only catches runtime errors in the current call level.This means, for example, that runtime errors resulting from

PERFORM- or CALL FUNCTION statements are not trapped by

CATCH ... ENDCATCH.

(for the list of standard runtime catchable errors refer to help)

COMMUNICATION:-

COMMUNICATION INIT DESTINATION dest ID id.

COMMUNICATION ALLOCATE ID id.

COMMUNICATION ACCEPT ID id.

COMMUNICATION SEND ID id BUFFER f.

COMMUNICATION RECEIVE ID id

...BUFFER f

...DATAINFO d

...STATUSINFO s.6. COMMUNICATION DEALLOCATE ID id.

The COMMUNICATION statement allows you to develop applications which perform direct program-to-program

communication. The basis for this is CPI-C (Common Programming Interface - Coummunication), defined by IBM

within the context of SAA standards as a standardized communications interface.

The COMMUNICATION statement provides the essential parameters for implementing simple communication. The

basis for this is the CPI-C starter set that covers the following functionality:

Establishing a connectionAccepting a communication

Sending data

Receiving data

Closing a connection

ABAP Tabstrip Control

Basic form CONTROLS ctrl TYPE TABSTRIP.

Effect Creates a control ctrl with type TABSTRIP.

1. PUT node.

2. PUT .

You can only use this statement in the database access program of a logical database whose structure contains the node

node. You use it to pass data read by the logical database to itsuser. This is either an executable (type 1) program with the logical database entered in its program attributes, or a

program that is using the function module LDB_PROCESS. In the first case (executable programs), the "PUT node." orPUT ." statement triggers the "GET node." event in the program. In the second case, the corresponding callback

routine is called, and the data from the work area node or is passed back to it.


28/33

STRING and XSTRING

The elementary data type STRING is similar to data type C and refers to a variable-length string. Accordingly, the

elementary data type XSTRING is similar to data type X and refers to a variable-length byte sequence.

Area Code DescriptionF FI - Financial Accounting

D DASS (Control Station)

A AM - Assets Management

K CO - Controlling

M MM - Materials Management

V SD - Sales and Distribution

C PP - Production Planning

I PM - Plant MaintenanceQ QM - Quality Management

P PS - Project SystemU Enterprise Data Model

G General Ledger (G/L)

S Basis

Y System

E EDI

X Cross Application

1 Environment Health & SafetyN HospitalR Human Resources

H Human Resources Planning

9 Industry Solution

L Inventory Management

W Merchandise Management System

J Publishing Work Flow

************************************************************************

* Program name: Program name - Program title

*

* Description: Description of program*

* Date/Author: Date Written/Authors name

*

* Table Updates: Listing of tables updated*

* Input Parameters: (For Includes/ Function Modules)*

* Output Parameters: (For Includes/Function Modules)

*

* Return Codes:

*

* Special Logic:

** Includes:************************************************************************

* M O D I F I C A T I O N L O G

************************************************************************

* Date Programmer Request # Description

* ------ -------------- ------------- ---------------------------*

* dd/mm/yy xxxxxxxxxxxxxx nnnnn New Program

*

************************************************************************REPORT YUPSTDS .

************************************************************************

* T A B L E S


29/33

************************************************************************

TABLES:

************************************************************************

* S E L E C T O P T I O N S

************************************************************************

SELECT-OPTIONS:

************************************************************************* P A R A M E T E R S

************************************************************************

PARAMETERS:

************************************************************************

* D A T A

************************************************************************

DATA:

** Accumulators **** Constants **

** Switches **** Work fields **

** Internal Tables **

** Data structures / Strings **

************************************************************************

* I N I T I A L I Z A T I O N

************************************************************************

INITIALIZATION.************************************************************************* A T S E L E C T I O N S C R E E N

************************************************************************

AT SELECTION-SCREEN.

************************************************************************

* T O P O F P A G E

************************************************************************

TOP-OF-PAGE.

************************************************************************* E N D O F P A G E

************************************************************************

END-OF-PAGE.

************************************************************************* S T A R T O F S E L E C T I O N

************************************************************************

START-OF-SELECTION.

************************************************************************* E N D O F S E L E C T I O N

************************************************************************END-OF-SELECTION.

************************************************************************

* F O R M S


30/33

To be determined by the clients business rules.

Short Name Med. Name Long Name Description

MAT MATRL MATERIAL Material

Flow Logic

*-------------------------------------------------------------------Process Before Output.

*

module SET_STATUS . " Called by all screens

* Enter screen specific modules here i.e. dynamic screen locking, etc.

*

*-------------------------------------------------------------------

Process After Input.

* Process fast-exit commandsmodule PAI_EXIT AT EXIT-COMMAND. " Called by all screens

* Save OK_CODE pressedmodule PAI_INITIALIZE. " Called by all screens

*

* Enter screen specific modules here i.e. Field checks, Loops, Table Controls etc.

*

* Process user command ( OK_CODE ) after all checks completed

module USER_COMMANDS.

Process Before Output Modules*-------------------------------------------------------------------***INCLUDE MZxxxO01 .

*-------------------------------------------------------------------

*&---------------------------------------------------------------------*

*& Module SET_STATUS OUTPUT

*&---------------------------------------------------------------------*

* text *

*----------------------------------------------------------------------*

MODULE SET_STATUS OUTPUT.CASE SY-DYNNR. " Interrogate screen number

WHEN '0100'. " Screen description for screen 100

SET PF-STATUS '100MAIN'.

SET TITLEBAR '100'.WHEN '0200'. " Screen description for screen 200

SET PF-STATUS '200MAIN'.

SET TITLEBAR '200'.

* Add any subsequent screensENDCASE.

ENDMODULE. " SET_STATUS OUTPUTProcess After Input Modules

*-------------------------------------------------------------------

***INCLUDE MZxxxI01 .

*-------------------------------------------------------------------

*&---------------------------------------------------------------------*

*& Module PAI_EXIT INPUT

*&---------------------------------------------------------------------** text **----------------------------------------------------------------------*

MODULE PAI_EXIT INPUT.

CASE SY-DYNNR. " Interrogate screen number

37719530 ABAP Programming Standards

Documents

Transcript of 37719530 ABAP Programming Standards