You have built ALV reports. But right now, they show every row in the table. No filters, no date range, no user input. That works for a demo — but in a real SAP system, users want to choose what they see.

Every report you build from now on will start with a selection screen — the input screen that appears before the report runs. It is how users enter filter criteria, dates, and ranges. And behind every selection screen are events that control what happens when: the screen loads, the user enters data, or the user clicks Execute.

This chapter teaches you the complete selection screen toolkit. By the end, you will be able to build interactive reports that accept user input and respond dynamically.

🎯 What You Will Learn in This Chapter

• What selection screens are and why every report needs one
• How to use PARAMETERS for single-value input
• How to use SELECT-OPTIONS for range input with operators
• The complete event flow: INITIALIZATION, AT SELECTION-SCREEN, START-OF-SELECTION, END-OF-SELECTION
• How to validate user input with field-level checks
• What PBO and PAI are and when they run
• How to save selection values as a Variant
• How to create a Transaction Code to launch your report directly

📘 What is a Selection Screen?

A selection screen is the input screen that SAP automatically generates from your ABAP program before the report runs. It is where users enter filter criteria — dates, IDs, ranges — that determine what data the report returns.

You do not design the selection screen manually. Instead, you declare PARAMETERS and SELECT-OPTIONS statements in your code. SAP reads these and builds the screen automatically.

The standard selection screen (1000)

Every ABAP report has a default selection screen numbered 1000. You do not need to create it manually — it appears as soon as you declare PARAMETERS or SELECT-OPTIONS. You can also create additional custom screens (1001, 1002, etc.) for multi-step input, but that is advanced and rarely needed at the beginner level.

🔤 PARAMETERS — Single-Value Input

PARAMETERS creates a single-value input field on the selection screen. Use it when the user needs to enter exactly one value — like a specific airline code, a plant, or a date.

Basic syntax

PARAMETERS: p_carrid TYPE scarr-carrid.

START-OF-SELECTION.
  SELECT * FROM scarr
    INTO TABLE @DATA(lt_scarr)
    WHERE carrid = @p_carrid.

  LOOP AT lt_scarr INTO DATA(ls_scarr).
    WRITE: / ls_scarr-carrid, ls_scarr-carrname.
  ENDLOOP.

Useful PARAMETERS additions

Example with options

PARAMETERS:
  p_carrid TYPE scarr-carrid OBLIGATORY,
  p_date   TYPE sy-datum DEFAULT sy-datum,
  p_active AS CHECKBOX DEFAULT 'X'.

🎯 SELECT-OPTIONS — Range Input with Operators

SELECT-OPTIONS creates a range input field. Users can specify complex criteria — equal to, greater than, between, not equal, and more. This is the most powerful and most common input type in SAP reports.

Basic syntax

SELECT-OPTIONS: s_carrid FOR scarr-carrid.

START-OF-SELECTION.
  SELECT * FROM scarr
    INTO TABLE @DATA(lt_scarr)
    WHERE carrid IN @s_carrid.

  LOOP AT lt_scarr INTO DATA(ls_scarr).
    WRITE: / ls_scarr-carrid, ls_scarr-carrname.
  ENDLOOP.

Useful SELECT-OPTIONS additions

Pre-fill with a range

SELECT-OPTIONS: s_date FOR sy-datum.

INITIALIZATION.
  s_date-sign   = 'I'.
  s_date-option = 'BT'.
  s_date-low    = sy-datum - 30.
  s_date-high   = sy-datum.
  APPEND s_date.

⚡ The Event Flow — What Runs When

ABAP reports are event-driven. SAP automatically runs certain blocks of code at specific moments. Understanding this flow is the key to building correct reports.

The main events, in order

Complete flow example

REPORT z_selection_screen_demo.

PARAMETERS: p_carrid TYPE scarr-carrid OBLIGATORY.
SELECT-OPTIONS: s_date FOR sy-datum.

" 1. Runs first — set defaults
INITIALIZATION.
  s_date-low = sy-datum - 30.
  s_date-high = sy-datum.
  APPEND s_date.

" 2. Runs after user clicks Execute — validate
AT SELECTION-SCREEN.
  IF p_carrid IS INITIAL.
    MESSAGE 'Airline code is required' TYPE 'E'.
  ENDIF.

" 3. Runs after validation passes — main logic
START-OF-SELECTION.
  WRITE: / 'Report started for airline:', p_carrid.

✅ Validating User Input

Never trust user input. Always validate it before the report processes data. Use AT SELECTION-SCREEN for validation.

Common validation patterns

AT SELECTION-SCREEN.
  " Check required field
  IF p_carrid IS INITIAL.
    MESSAGE 'Please enter an airline code' TYPE 'E'.
  ENDIF.

  " Check if value exists in database
  SELECT SINGLE carrid FROM scarr
    INTO @DATA(lv_check)
    WHERE carrid = @p_carrid.
  IF sy-subrc <> 0.
    MESSAGE 'Airline code does not exist' TYPE 'E'.
  ENDIF.

  " Date range validation
  IF s_date-low > s_date-high.
    MESSAGE 'From-date cannot be after to-date' TYPE 'E'.
  ENDIF.

🔄 PBO and PAI — Screen Flow Logic

Selection screen 1000 is technically a screen, and all screens in SAP follow a flow logic with two events: PBO (Process Before Output) and PAI (Process After Input).

In classic screen programming (using transaction SE51), you write PBO and PAI modules to control this flow. In ABAP reports with selection screens, you rarely write PBO/PAI directly — the events AT SELECTION-SCREEN OUTPUT and AT SELECTION-SCREEN handle the same concepts.

Mapping to selection screen events

💾 Variants — Saving Selection Screen Values

A Variant is a saved set of selection screen values. Users can save a variant once and reuse it many times — saving them from re-entering the same filter criteria every time.

How users save a variant

1. Fill in the selection screen with the desired values
2. Click Save (or press Ctrl+S) on the selection screen toolbar
3. Give the variant a name and description
4. Choose whether to make it the default

How developers manage variants

• SE38 — In the program’s attribute screen, click Variants
• SE93 — When creating a T-code, you can assign a default variant
• Programmatically — Use function modules RS_VARIANT_CATALOG or RS_VARIANT_EXISTENCE_CHECK

🚀 Transaction Codes — Launching Your Report

Users do not want to type SE38, then enter your program name, then click Execute. They want to type a short code in the command field and hit Enter. That is what a Transaction Code (T-code) gives them.

Creating a T-code — Steps

📝 Chapter Summary

• Selection screens are the input screens that appear before a report runs. They are auto-generated from PARAMETERS and SELECT-OPTIONS.
• PARAMETERS creates a single-value input field. Use it for exactly-one-value criteria.
• SELECT-OPTIONS creates a range input field with operators (EQ, BT, GT, etc.). Use it for filtering.
• The four main events run in this order: INITIALIZATION → AT SELECTION-SCREEN → START-OF-SELECTION → END-OF-SELECTION.
• AT SELECTION-SCREEN is the right place to validate user input. Use MESSAGE ... TYPE 'E' to stop the report on invalid input.
• PBO (Process Before Output) = AT SELECTION-SCREEN OUTPUT. PAI (Process After Input) = AT SELECTION-SCREEN.
• Variants let users save selection screen values for reuse.
• Transaction Codes (SE93) let users launch your report with a short code instead of navigating SE38.