Internal Tables

Internal tables are the central data structure in ABAP. Most of what an ABAP program does is manipulate them.

Three kinds

Internal table kinds

Kind	Key	Search	Duplicates	Use
STANDARD	Non-unique	Linear	Allowed	Sequential processing, index access
SORTED	Unique or non-unique	Binary	Configurable	Frequent key lookups, always sorted
HASHED	Unique required	Hash	Not allowed	Fast lookup by full key

Adding rows

Insertion

APPEND ls_item TO lt_items.
INSERT ls_item INTO TABLE lt_sorted.
APPEND LINES OF lt_source TO lt_target.

DATA(lt_items) = VALUE ty_items(
  ( matnr = 'MAT-001' menge = 10 )
  ( matnr = 'MAT-002' menge = 20 ) ).

APPEND is not available on sorted or hashed tables, because position is determined by the key rather than by insertion order.

Reading rows

Reading

READ TABLE lt_items INTO ls_item WITH KEY matnr = 'MAT-001'.
IF sy-subrc = 0.
ENDIF.

READ TABLE lt_items ASSIGNING FIELD-SYMBOL(<fs>) WITH KEY matnr = 'MAT-001'.

READ TABLE lt_items TRANSPORTING NO FIELDS WITH KEY matnr = 'MAT-001'.

DATA(ls_found) = lt_items[ matnr = 'MAT-001' ].

Changing and deleting

Modification

MODIFY lt_items FROM ls_item TRANSPORTING menge WHERE matnr = 'MAT-001'.

DELETE lt_items WHERE menge = 0.

SORT lt_items BY matnr.
DELETE ADJACENT DUPLICATES FROM lt_items COMPARING matnr.

CLEAR lt_items.
FREE  lt_items.

Aggregating

Control level processing

SORT lt_items BY matnr.
LOOP AT lt_items INTO ls_item.
  AT NEW matnr.
    lv_subtotal = 0.
  ENDAT.

  lv_subtotal = lv_subtotal + ls_item-menge.

  AT END OF matnr.
    WRITE: / ls_item-matnr, lv_subtotal.
  ENDAT.
ENDLOOP.

DATA(lv_total) = REDUCE i( INIT s = 0
                           FOR ls IN lt_items
                           NEXT s = s + ls-menge ).

📖 Unfamiliar term? Look it up in the SAP glossary.