Today we move into core ABAP programming fundamentals.

If you understand Day-10 clearly, you can write basic SAP reports confidently.

We will cover:

• ✅ Datatypes

• ✅ Variables

• ✅ TYPES (Structure creation)

• ✅ Internal Tables

• ✅ PARAMETERS

• ✅ SELECT-OPTIONS

• ✅ LOOP

• ✅ IF Conditions

• ✅ BREAK-POINT

• ✅ Input & Output

• ✅ Selection Screen Frames

Everything explained in simple language 👇

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1️⃣ What is a Datatype in ABAP?

A datatype defines what kind of data a variable can store.

Think like this:

• i → Whole numbers (10, 20, 100)

• string → Text

• p → Decimal numbers (money)

• abap_bool → True / False

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Basic Datatypes Example

DATA: gv_text   TYPE string,        "Stores text
      gv_count  TYPE i,             "Stores integer numbers
      gv_price  TYPE p DECIMALS 2,  "Stores decimal values
      gv_flag   TYPE abap_bool.     "True or False

Explanation:

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2️⃣ Creating a File Name Variable

DATA: gv_filename TYPE string.

gv_filename = '/usr/sap/tmp/flight_data.txt'.

This stores a file path.

Used in:

• File upload

• File download

• Application server file handling

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3️⃣ TYPES – Creating Custom Structure

In ABAP, TYPES is used to create a structure.

Structure = Group of fields.

Example:

TYPES: BEGIN OF ty_flight,
         carrid TYPE sflight-carrid,
         connid TYPE sflight-connid,
         price  TYPE sflight-price,
       END OF ty_flight.

Explanation:

• sflight → Standard SAP flight table

• We are copying its field definitions

• Ensures datatype consistency

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4️⃣ Internal Table & Work Area

Internal Table = Stores multiple rows
Work Area = Stores one row

DATA: it_flight TYPE STANDARD TABLE OF ty_flight,
      wa_flight TYPE ty_flight.

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5️⃣ PARAMETERS & SELECT-OPTIONS

These create input fields on selection screen.

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PARAMETERS

Used for single input.

PARAMETERS: p_carr TYPE sflight-carrid.

User enters one airline.

Example input:

LH

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SELECT-OPTIONS

Used for range input.

SELECT-OPTIONS: s_price FOR sflight-price.

User can enter:

• Single value

• Multiple values

• Range (100 to 500)

• Exclude values

Example:

100 – 800

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6️⃣ Selection Screen Frame

To group fields:

SELECTION-SCREEN BEGIN OF BLOCK b1 WITH FRAME TITLE text-001.
  PARAMETERS: p_max TYPE i DEFAULT 5.
SELECTION-SCREEN END OF BLOCK b1.

Creates a box around selection fields.

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7️⃣ BREAK-POINT (Debugging)

BREAK-POINT.

Stops program execution for debugging.

Used in:

• Testing

• Error checking

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8️⃣ SELECT Statement (Database Fetch)

SELECT carrid
       connid
       price
  FROM sflight
  INTO TABLE it_flight
  UP TO p_max ROWS
  WHERE carrid = p_carr
    AND price IN s_price.

What happens here?

• Fetch data from SFLIGHT

• Apply filter

• Store in internal table

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9️⃣ LOOP Processing

LOOP AT it_flight INTO wa_flight.

Reads internal table row by row.

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🔟 IF Condition

IF wa_flight-price > 500.
  gv_flag = abap_true.
ELSE.
  gv_flag = abap_false.
ENDIF.

Simple logic:

If price > 500 → True
Else → False

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1️⃣1️⃣ WRITE (Output)

WRITE: / wa_flight-carrid,
         wa_flight-connid,
         wa_flight-price,
         gv_flag.

/ → New line

Displays output in classic list format.

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1️⃣2️⃣ System Function Example

WRITE: / 'Total Records:', lines( it_flight ).

lines( ) returns number of rows.

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🧠 Complete Beginner Version of Code

Here is the full clean program:

REPORT z_abap_all_basics_demo.

* Variables
DATA: gv_flag TYPE abap_bool.

* Structure
TYPES: BEGIN OF ty_flight,
         carrid TYPE sflight-carrid,
         connid TYPE sflight-connid,
         price  TYPE sflight-price,
       END OF ty_flight.

* Internal table
DATA: it_flight TYPE STANDARD TABLE OF ty_flight,
      wa_flight TYPE ty_flight.

* Selection screen
PARAMETERS: p_carr TYPE sflight-carrid.
SELECT-OPTIONS: s_price FOR sflight-price.

* Fetch data
SELECT carrid connid price
  INTO TABLE it_flight
  FROM sflight
  WHERE carrid = p_carr
    AND price IN s_price.

* Loop
LOOP AT it_flight INTO wa_flight.

  IF wa_flight-price > 500.
    gv_flag = abap_true.
  ELSE.
    gv_flag = abap_false.
  ENDIF.

  WRITE: / wa_flight-carrid,
           wa_flight-connid,
           wa_flight-price,
           gv_flag.

ENDLOOP.

WRITE: / 'Total Records:', lines( it_flight ).

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🎯 Final Understanding

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🚀 Real-World Usage

Used in:

• Reports

• ALV

• Data filtering

• Custom SAP programs

• Business reporting