Solve with Alter

Three important statement used in module pool for screen . Leave screen - call screen     - set screen      -

Chain & Endchain use for validation of field . Sometimes we want to check several fields as a group. To do this, include the fields in a FIELD statement, and enclose everything in a CHAIN-ENDCHAIN block. Example **** Screen flow logic: **** CHAIN. FIELD: SPFLI-CARRID, SPFLI-CONNID. MODULE CHECK_FLIGHT. ENDCHAIN. When an error is found inside a chain, the screen is re-displayed, and all fields found anywhere in the chain are input-enabled. All non-chain fields remain disabled.

For select options, create sub-screen area in your screen layout where you want to create the select options. In the top include of your module pool program declare a selection screen as a sub-screen e.g. SELECTION-SCREEN BEGIN OF SCREEN 100 AS SUBSCREEN. Select-options s_matnr for mara-matnr. SELECTION-SCREEN END OF SCREEN.  In the PBO and PAI of the main screen where the select options needs to be created do a call subscreen of the above screen (100). CALL SUBCREEN sub_area INCLUDING. This call subscreen statement is necessary for transport of values between screen and program. All validations of the selection screen fields e.g. the s_matnr field created above should be done in selection screen events like AT SELECTION-SCREEN etc. and not in PAI. These selection screen validations etc. should be done in the top include only .

F   Table control there must be a loop statement in both PBO and PAI. It is because loop statement causes screen fields to be copied back and forth between ABAP program and the Screen Field. At the time of PBO, the transport of the table control fields from the ABAP program to the screen takes place after every loop run in the flow logic. The remaining screen fields are filled, as usual, at the end of PBO processing. At PAI time, first all the screen fields that do not belong to any table control and not listed in any FIELD statement are transported to identically-named fields of the ABAP program. The contents of the table control fields are transported, row by row at the beginning of the corresponding loop run, into the identically-names fields of the ABAP program. The fields that are listed in the FIELD statements are transported, as usual, directly from the corresponding FIELD statement. Within the loops, two system fields are...

Event Of Module Pool - PAI & PBO is working as name states . PBO ( Process Before Output ) -  PAI  ( Process After Input   ) - POH (Process on Help-Request)     - It gives F1 details .    for calling -        Process on Help-Request .           Module f1_help_field2 Input . example - two functional module use for help  .           Module f1_help_field2 Input .                     call functional 'Help_object_show_for_field'                             exporting                   ...

Delivery Class - it help in managing transport of table data when installation or upgrade in a client copy or when transporting between customer system . Type of delivery Class- 7 types of delivery class available 1- Application Table (1 type ) 2- System Table (2 type) 3- Customer Table (4 Type ) Data Class - It is specify the database physical area where the table is stored .