• Types of ABAP Processing Blocks
  All ABAP programs are made up of processing blocks. You cannot nest processing blocks. When a program is executed, its processing blocks are called. All of the statements in an ABAP program, apart from its global data declarations, belong to a processing block.

• Screens: Defined using the Screen Painter. Can be combined into screen sequences. You can use CALL SCREEN or a transaction code to call it. It can be processed in dialog modules.
• Selection Screen: Defined within an ABAP program. Called by the runtime environment or by the CALL SELECTION-SCREEN statement. Processed in event blocks of the corresponding ABAP program.
• Lists: Defined within an ABAP program. Called by the runtime environment. Processed in event blocks of the corresponding ABAP program.

ABAP system fields are always available in ABAP programs. The runtime system fills them according to context. They can then be used in programs to query the system status. System fields are variables but you should always treat them as though they were constants, and only read them. If you change their values, important information for the flow of the program may be lost. In exceptional circumstances, system fields may be overwritten in an ABAP program to control the system – for example, SY-LSIND (for navigating to a detail list).

With one exception the names and data types of the system fields are stored in the ABAP Dictionary in the SYST structure and realized as components of the predefined structure SY in ABAP programs.

The system field SY-REPID is not part of SYST or SY. Instead, every program contains the predefined constants SY-REPID and SYST-REPID, which both contain the name of the corresponding program. Furthermore, there are two predefined types of the same name, SY-REPID and SYST-REPID.

All system fields are addressed using SY field name and their types using SYST field name.

*To turn runtim analysis on within ABAP code insert the following code
SET RUN TIME ANALYZER ON.

*To turn runtim analysis off within ABAP code insert the following code
SET RUN TIME ANALYZER OFF.

In release 6.10 a new exception concept has been introduced. Please find below a basic syntax of how
to code the new error-handling concept.

The purpose of the SAP Query are for users with no programming knowledge.  It is also used by abapers to create simple reports for the users.

You can easily create three types of query reports :

1.  Basic lists (details list)
2.  Statistics (counting etc.)
3.  Ranked lists 

When you start using version 4.6x, you can see a Quick Viewer button in the Query Main screen. It is suppose to be much simplier that the original Query but it is up to you to decide whether is it true.

To create a report with the QuickViewer, all you need to to do is enter texts such as titles, and select the fields and options that define the structure of the report. You can assign a specific sequence to the fields by numbering them.

If necessary, you can edit the lists either through drag and drop in WYSIWYG mode, or by using the functions in the available toolbars. Data can also be send to external programs such as MS Excel or MS Word for further processing.

The only problem with QuickViewer is that it cannot read cluster table.

DBCON
Description of database connections (including password)

DD02V
Date dictionary tables

DD03L
Date dictionary tables and fields

DD07T
Texts for Domain Fixed Values

T100
Table of message ( mesage class and message number )

TRDIR
Table of programs

TRMAC
Table of macros

TSTC
Table of transaction codes

TADIR
Directory of R/3 repository objects

TFACD
Factory calender definition

THOCI
Public holiday calendar index

TPARA
Table of PID's

DEVACCESS
Table of development users including registered Developer access key

USR02
Logon data

USR04
User master authorization (one row per user)

UST04
User profiles (multiple rows per user)

USR10
Authorisation profiles (i.e. &_SAP_ALL)

UST10C
Composit profiles (i.e. profile has sub profile)

USR11
Text for authorisation profiles

USR12
Authorisation values

USR13
Short text for authorisation

USR40
Table for illegal passwords

OBJT
Authorisation objetc table

If you are not authorised to change table entries or the table has been create without table maintenance
allowed (all SAP tables), you can still change entries via data browser (SE16) by means of debugging. The
process is as follows:

This transaction allows a user to record keystrokes and other keyboard actions so that they may be incorporated into a BDC session. While any session may be recorded, it does not mean that the recording can be used to create a session. Within a recording individual screens may not be allowed.

Customized screens may present a problem. Only use the non-customized screens to record sessions.

Runtime errors can occur during execution of bundled updates. How are they handled? In general, COMMIT WORK processing occurs in the following order:

...

1. All dialog-task FORM routines logged with PERFORM ON COMMIT are executed.

2. All high-priority (V1) update-task function modules are executed.

The end of V1-update processing marks the end of the change transaction. If you used COMMIT WORK AND WAIT to trigger commit processing, control returns to the dialog-task program.

3. All low-priority (V2) update-task function modules are triggered.
All background-task function modules are triggered.

Runtime errors can occur either in the system itself, or because your program issues an termination message (MESSAGE type ‘A’). Also, the ROLLBACK WORK statement automatically signals a runtime error. The system handles errors according to where they occur:

Sometimes you need to replace a carriage retun or line feed in a string. (These can screw around with EDI IDocs etc...) This is how you do it...