1. What is a Variable in ABAP?

A variable is a named memory location used to store data during program execution. Its value can change while the program runs.

✅ Syntax

DATA variable_name TYPE data_type VALUE initial_value.

✅ Example

DATA gv_total TYPE i VALUE 10.

gv_total = gv_total + 5.
WRITE: / gv_total.

Output:

15

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Types of Variables in ABAP

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1️⃣ Local Variables

• Declared using DATA

• Exist only within the program block

• Recreated each time block runs

FORM calculate.
  DATA lv_sum TYPE i.
  lv_sum = 10 + 20.
  WRITE: / 'Sum:', lv_sum.
ENDFORM.

✔ lv_sum exists only inside FORM.

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2️⃣ Static Variables

• Retain value between calls

• Declared using STATICS

FORM counter.
  STATICS lv_count TYPE i.
  lv_count = lv_count + 1.
  WRITE: / 'Counter:', lv_count.
ENDFORM.

Each time counter runs → value increases.

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3️⃣ Reference Variables

Used in Object-Oriented ABAP

DATA lr_obj TYPE REF TO object.
CREATE OBJECT lr_obj.

Stores a reference (pointer), not actual data.

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4️⃣ System Variables (sy- fields)

Automatically maintained by SAP.

WRITE: / 'User:', sy-uname,
       / 'Date:', sy-datum.

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5️⃣ Structured Variables

Used to group multiple fields.

TYPES: BEGIN OF ty_employee,
         emp_id   TYPE i,
         emp_name TYPE string,
         age      TYPE i,
       END OF ty_employee.

DATA ls_emp TYPE ty_employee.

ls_emp-emp_id = 101.
ls_emp-emp_name = 'Harish'.
ls_emp-age = 25.

WRITE: / ls_emp-emp_name.

2. What are Literals?

Literals are fixed values written directly in code.

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🔸 Numeric Literals

DATA lv_num TYPE i VALUE 100.
DATA lv_pack TYPE p DECIMALS 2 VALUE '1234.50'.

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🔸 Character Literals

Always enclosed in ' '.

DATA lv_text TYPE string VALUE 'Hello ABAP'.

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3. What are Constants?

A constant is a fixed value that cannot change.

✅ Syntax

CONSTANTS constant_name TYPE type VALUE value.

✅ Example

CONSTANTS c_tax TYPE p DECIMALS 2 VALUE '0.18'.

If you try to change it:

c_tax = 0.20.   " ❌ Error

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🔎 Variable vs Constant

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4. Data Types in ABAP

Elementary Types

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Example

DATA lv_date TYPE d.
lv_date = sy-datum.
WRITE: / lv_date.

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Complex Types

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Structure

TYPES: BEGIN OF ty_emp,
         empid TYPE i,
         name  TYPE string,
       END OF ty_emp.

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Internal Table

DATA lt_emp TYPE TABLE OF ty_emp.
DATA ls_emp TYPE ty_emp.

ls_emp-empid = 1.
ls_emp-name = 'John'.

APPEND ls_emp TO lt_emp.

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5. Input Methods in ABAP

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PARAMETERS

PARAMETERS p_name TYPE string.

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SELECT-OPTIONS

SELECT-OPTIONS s_date FOR sy-datum.

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Radio Buttons

PARAMETERS r_yes RADIOBUTTON GROUP g1.

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6. Arithmetic Operators

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Example

DATA: a TYPE i VALUE 10,
      b TYPE i VALUE 3,
      result TYPE i.

result = a MOD b.
WRITE result.

Output:

1

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7. Comparison Operators

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Example

IF a > b.
  WRITE 'A is greater'.
ENDIF.

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8. String Operators

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Example

DATA lv_full TYPE string.
lv_full = 'John' && ' ' && 'Doe'.
WRITE lv_full.

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9. Modern Operators (7.4+)

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VALUE Operator

DATA lt_numbers TYPE TABLE OF i.

lt_numbers = VALUE #( ( 1 ) ( 2 ) ( 3 ) ).

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REDUCE Operator

DATA lv_sum TYPE i.

lv_sum = REDUCE i(
  INIT x = 0
  FOR wa IN lt_numbers
  NEXT x = x + wa ).

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COND (Ternary Alternative)

DATA lv_result TYPE string.

lv_result = COND string(
  WHEN a > b THEN 'Greater'
  ELSE 'Smaller' ).

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10. Types of SELECT in ABAP

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1. Basic SELECT

SELECT carrid carrname
  FROM scarr
  INTO TABLE @DATA(lt_carrier).

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2. SELECT SINGLE

SELECT SINGLE *
  FROM scarr
  INTO @DATA(ls_scarr)
  WHERE carrid = 'LH'.

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3. SELECT DISTINCT

SELECT DISTINCT carrid
  FROM sflight
  INTO TABLE @DATA(lt_unique).

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4. ORDER BY

SELECT carrid carrname
  FROM scarr
  INTO TABLE @DATA(lt_scarr)
  ORDER BY carrname ASCENDING.

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5. GROUP BY

SELECT carrid, COUNT(*) AS total
  FROM sflight
  GROUP BY carrid
  INTO TABLE @DATA(lt_group).

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6. INNER JOIN

SELECT a~carrid, b~fldate
  FROM scarr AS a
  INNER JOIN sflight AS b
  ON a~carrid = b~carrid
  INTO TABLE @DATA(lt_join).

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7. LEFT OUTER JOIN

SELECT a~carrid, b~fldate
  FROM scarr AS a
  LEFT OUTER JOIN sflight AS b
  ON a~carrid = b~carrid
  INTO TABLE @DATA(lt_join).

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8. FOR ALL ENTRIES

⚠ Always check internal table not empty.

IF lt_scarr IS NOT INITIAL.

  SELECT carrid fldate
    FROM sflight
    INTO TABLE @DATA(lt_flight)
    FOR ALL ENTRIES IN @lt_scarr
    WHERE carrid = @lt_scarr-carrid.

ENDIF.

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⚠ Important Rule for FOR ALL ENTRIES

If internal table is empty → system fetches ALL records.

Always write:

IF lt_table IS NOT INITIAL.

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🎯 Final Understanding

Day 12 covers the core foundation of ABAP programming:

✔ Variables & Memory ✔ Constants vs Variables ✔ Data Types (Elementary & Complex) ✔ Operators (Arithmetic, Logical, String) ✔ Modern ABAP Operators ✔ SELECT Variants ✔ GROUP BY & ORDER BY ✔ JOINS ✔ FOR ALL ENTRIES