When the user starts an executable (type 1) program, the program context and memory space for data objects (variables and structures) are made available on the application server. The subsequent program flow is controlled by the ABAP run time system.If the program contains a selection screen, the ABAP run time system sends it to the presentation server at the start of the program.
Once the user has finished entering data on the selection screen, he or she chooses 'Execute' to tell the system to start processing the rest of the program. The data entered on the selection screen is automatically placed in the corresponding data objects. The ABAP run Time system takes over control of the program.In this simple example, there is only one ABAP processing block to be processed by the runtime system.This processing block contains a read access to the database. The program sends information to the database about the records that should be read.
The database returns the required database records and the run time system ensures that the data is placed in the relevant data objects.The list output is also programmed in the processing block. After the processing block finishes, the run time system sends the list as a screen to the presentation server.Selection screens allow users to enter ranges of values. They are normally used to define the set of data that needs to be read from the database.
As well as the normal graphical elements (group boxes, check boxes, radio buttons, and so on) that you use in screens, selection screens also have input/output fields (PARAMETERS) and special groups of input/output fields (SELECT-OPTIONS).
You place a single input/output field on the selection screen using the PARAMETERS statement.
You can use the SELECT-OPTIONS statement to place a group of fields on the screen that allows users to enter complex selections. The selection may be a single value, or any form of interval (discrete or continuous). You can also use patterns. (See following slides).
You can create variants for selection screens.If you declare an input field with reference to an ABAP Dictionary field, any search helps defined for the Dictionary field will be available on the selection screen.Selection texts can be translated into other languages. They are then displayed in the user's logon language.
Selection ranges are stored in programs using an internal table.The ABAP statement SELECT-OPTIONS
MySAP CRM System architecture and design
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