ABAP Internal Tables - Complete Reference
Source: https://github.com/SAP-samples/abap-cheat-sheets/blob/main/01_Internal_Tables.md
Table of Contents
- Table Type Categories
- Declaration Syntax
- Table Keys
- Creating and Populating Tables
- Reading Table Entries
- Modifying Table Entries
- Deleting Table Entries
- Looping and Iteration
- Sorting Tables
- Table Functions
- FILTER Expression
- Group Processing
- Secondary Table Keys
- Performance Considerations
Table Type Categories
Standard Tables
- Index access and key access
- Non-unique primary key (always)
- Suitable for sequential processing and when duplicates allowed
- Default table type
Sorted Tables
- Index access and key access
- Unique or non-unique primary key
- Automatically sorted by key
- Binary search for key access (O(log n))
Hashed Tables
- Key access only (no index access)
- Unique primary key required
- Hash algorithm for constant-time access (O(1))
- Best for large datasets with unique key access
Declaration Syntax
" Using TYPE TABLE OF
DATA itab TYPE TABLE OF string WITH EMPTY KEY.
DATA std_tab TYPE STANDARD TABLE OF zdemo_struc WITH EMPTY KEY.
DATA sorted_tab TYPE SORTED TABLE OF zdemo_struc WITH UNIQUE KEY id.
DATA hashed_tab TYPE HASHED TABLE OF zdemo_struc WITH UNIQUE KEY id.
" With DDIC types
DATA itab TYPE zdemo_table_type.
" Inline declarations
DATA(itab) = VALUE string_table( ( `a` ) ( `b` ) ( `c` ) ).
" Structured line type
DATA: BEGIN OF line,
id TYPE i,
name TYPE string,
END OF line.
DATA itab TYPE TABLE OF line WITH EMPTY KEY.
" Reference to internal table
DATA itab_ref TYPE REF TO string_table.
itab_ref = REF #( itab ).Table Keys
Primary Key
" Empty key (standard tables only)
DATA itab TYPE TABLE OF struc WITH EMPTY KEY.
" Single key field
DATA itab TYPE SORTED TABLE OF struc WITH UNIQUE KEY id.
" Composite key
DATA itab TYPE HASHED TABLE OF struc WITH UNIQUE KEY client id.
" Non-unique key (sorted tables)
DATA itab TYPE SORTED TABLE OF struc WITH NON-UNIQUE KEY category.
" Default key (all non-numeric fields)
DATA itab TYPE TABLE OF struc WITH DEFAULT KEY.Secondary Keys
" Sorted secondary key
DATA itab TYPE TABLE OF struc
WITH EMPTY KEY
WITH NON-UNIQUE SORTED KEY by_name COMPONENTS name.
" Hashed secondary key
DATA itab TYPE TABLE OF struc
WITH EMPTY KEY
WITH UNIQUE HASHED KEY by_id COMPONENTS id.
" Multiple secondary keys
DATA itab TYPE SORTED TABLE OF struc
WITH UNIQUE KEY id
WITH NON-UNIQUE SORTED KEY by_cat COMPONENTS category
WITH UNIQUE HASHED KEY by_code COMPONENTS code.
" Using secondary keys
READ TABLE itab WITH KEY by_name COMPONENTS name = 'Test' INTO wa.
LOOP AT itab USING KEY by_cat WHERE category = 'A'.
...
ENDLOOP.Creating and Populating Tables
VALUE Operator
" Simple values
DATA(itab) = VALUE string_table( ( `one` ) ( `two` ) ( `three` ) ).
" Structured entries
DATA(itab) = VALUE itab_type(
( id = 1 name = `First` )
( id = 2 name = `Second` )
( id = 3 name = `Third` ) ).
" BASE - append to existing
itab = VALUE #( BASE itab ( id = 4 name = `Fourth` ) ).
" LINES OF - copy from other tables
itab = VALUE #( BASE itab ( LINES OF other_itab ) ).
" FOR iterations
DATA(itab) = VALUE itab_type(
FOR i = 1 UNTIL i > 10
( id = i name = |Entry { i }| ) ).
" FOR with source table
DATA(new_tab) = VALUE target_type(
FOR wa IN source_tab
( id = wa-key text = wa-description ) ).
" FOR with WHERE
DATA(filtered) = VALUE itab_type(
FOR wa IN source WHERE ( status = 'A' )
( wa ) ).APPEND and INSERT
" APPEND - add to end
APPEND VALUE #( id = 1 ) TO itab.
APPEND wa TO itab.
APPEND INITIAL LINE TO itab.
APPEND INITIAL LINE TO itab ASSIGNING FIELD-SYMBOL(<new>).
APPEND LINES OF source_itab TO itab.
APPEND LINES OF source FROM 5 TO 10 TO itab.
" INSERT - position-specific or key-based
INSERT wa INTO itab INDEX 1.
INSERT wa INTO TABLE itab. " Key-based for sorted/hashed
INSERT LINES OF source INTO itab INDEX 3.
INSERT LINES OF source INTO TABLE itab.CORRESPONDING Operator
" Basic mapping
target = CORRESPONDING #( source ).
" With BASE
target = CORRESPONDING #( BASE ( target ) source ).
" Field mapping
target = CORRESPONDING #( source MAPPING
target_field = source_field
other_field = another_field ).
" EXCEPT - exclude fields
target = CORRESPONDING #( source EXCEPT field1 field2 ).
" DEEP - handle nested structures
target = CORRESPONDING #( DEEP source ).
" DISCARDING DUPLICATES
itab = CORRESPONDING #( source DISCARDING DUPLICATES ).Reading Table Entries
Table Expressions (Recommended)
" By index
DATA(line) = itab[ 1 ].
DATA(line) = itab[ lines( itab ) ]. " Last line
" By key
DATA(line) = itab[ id = 1 ].
DATA(line) = itab[ id = 1 name = 'Test' ].
" Using secondary key
DATA(line) = itab[ KEY by_name name = 'Test' ].
" Safe access with OPTIONAL (returns initial if not found)
DATA(line) = VALUE #( itab[ id = 999 ] OPTIONAL ).
" Safe access with DEFAULT
DATA(line) = VALUE #( itab[ id = 999 ] DEFAULT VALUE #( id = 0 ) ).
" Accessing components
DATA(name) = itab[ 1 ]-name.
DATA(count) = itab[ KEY by_id id = 1 ]-count.
" Check existence
IF line_exists( itab[ id = 1 ] ).
...
ENDIF.
" Get index
DATA(idx) = line_index( itab[ name = 'Test' ] ).READ TABLE Statement
" Into work area
READ TABLE itab INTO wa INDEX 1.
READ TABLE itab INTO wa WITH KEY id = 1.
READ TABLE itab INTO wa WITH TABLE KEY id = 1.
" Into field symbol (recommended for modification)
READ TABLE itab ASSIGNING FIELD-SYMBOL(<fs>) INDEX 1.
READ TABLE itab ASSIGNING <fs> WITH KEY id = 1.
" Into data reference
READ TABLE itab REFERENCE INTO dref INDEX 1.
" Transporting specific fields
READ TABLE itab INTO wa TRANSPORTING name email.
READ TABLE itab TRANSPORTING NO FIELDS WITH KEY id = 1.
" Using secondary key
READ TABLE itab USING KEY by_name INTO wa WITH KEY by_name COMPONENTS name = 'Test'.
" Binary search (standard tables)
READ TABLE itab INTO wa WITH KEY name = 'Test' BINARY SEARCH.
" Check sy-subrc after READ
IF sy-subrc = 0.
" Found at sy-tabix
ELSE.
" Not found
ENDIF.Modifying Table Entries
Direct Modification
" Modify by index
itab[ 1 ]-name = 'Updated'.
itab[ 1 ] = VALUE #( id = 1 name = 'New' ).
" Modify via field symbol
READ TABLE itab ASSIGNING FIELD-SYMBOL(<fs>) INDEX 1.
<fs>-name = 'Updated'.
<fs>-count += 1.
" Modify in LOOP
LOOP AT itab ASSIGNING FIELD-SYMBOL(<line>).
<line>-name = to_upper( <line>-name ).
<line>-updated = abap_true.
ENDLOOP.MODIFY Statement
" Modify by index
MODIFY itab FROM wa INDEX 5.
" Modify by key (sorted/hashed tables)
MODIFY TABLE itab FROM wa.
" Modify transporting specific fields
MODIFY itab FROM wa INDEX 5 TRANSPORTING name email.
MODIFY TABLE itab FROM wa TRANSPORTING status.
" Modify with WHERE
MODIFY itab FROM VALUE #( status = 'X' )
TRANSPORTING status WHERE category = 'A'.Deleting Table Entries
" Delete by index
DELETE itab INDEX 1.
DELETE itab FROM 5 TO 10.
" Delete by key
DELETE TABLE itab FROM wa.
DELETE TABLE itab WITH TABLE KEY id = 1.
" Delete with WHERE
DELETE itab WHERE status = 'D'.
DELETE itab WHERE amount < 0 AND category <> 'X'.
" Delete adjacent duplicates (requires sorted table or prior SORT)
SORT itab BY name.
DELETE ADJACENT DUPLICATES FROM itab COMPARING name.
DELETE ADJACENT DUPLICATES FROM itab COMPARING ALL FIELDS.
" Clear table
CLEAR itab.
FREE itab. " Also releases memoryLooping and Iteration
LOOP Statement
" Basic loop
LOOP AT itab INTO wa.
" Process wa
ENDLOOP.
" With field symbol (recommended)
LOOP AT itab ASSIGNING FIELD-SYMBOL(<fs>).
<fs>-counter += 1.
ENDLOOP.
" With data reference
LOOP AT itab REFERENCE INTO DATA(dref).
dref->*-status = 'P'.
ENDLOOP.
" With WHERE condition
LOOP AT itab INTO wa WHERE status = 'A'.
...
ENDLOOP.
" Using secondary key
LOOP AT itab INTO wa USING KEY by_category WHERE category = 'X'.
...
ENDLOOP.
" With FROM/TO
LOOP AT itab INTO wa FROM 5 TO 10.
...
ENDLOOP.
" Group processing
LOOP AT itab INTO wa GROUP BY wa-category.
" wa is representative line
LOOP AT GROUP wa INTO DATA(member).
" Process each group member
ENDLOOP.
ENDLOOP.
" Available sy fields in loop
" sy-tabix - current index
" sy-index - loop counter (also works for DO/WHILE)FOR Expressions
" Transform table
DATA(new_tab) = VALUE itab_type(
FOR wa IN itab
( id = wa-id name = to_upper( wa-name ) ) ).
" Filter and transform
DATA(active) = VALUE itab_type(
FOR wa IN itab WHERE ( active = abap_true )
( id = wa-id status = 'Active' ) ).
" With INDEX INTO
DATA(numbered) = VALUE itab_type(
FOR wa IN itab INDEX INTO idx
( line_no = idx content = wa ) ).
" Nested FOR
DATA(product) = VALUE itab_type(
FOR a IN itab_a
FOR b IN itab_b
( a = a b = b result = a * b ) ).
" REDUCE aggregation
DATA(sum) = REDUCE i( INIT s = 0
FOR wa IN itab
NEXT s = s + wa-amount ).
DATA(max) = REDUCE i( INIT m = 0
FOR wa IN itab
NEXT m = COND #( WHEN wa-value > m THEN wa-value ELSE m ) ).
DATA(concat) = REDUCE string( INIT str = ``
FOR wa IN itab
NEXT str = str && wa-name && `, ` ).Sorting Tables
" Sort by field(s)
SORT itab BY name.
SORT itab BY category name.
SORT itab BY amount DESCENDING.
SORT itab BY name ASCENDING amount DESCENDING.
" Sort by table key
SORT itab BY PRIMARY KEY.
" Stable sort (preserve original order for equal elements)
SORT itab BY category STABLE.
" Case-insensitive sort
SORT itab BY name AS TEXT.Table Functions
" Count lines
DATA(count) = lines( itab ).
DATA(count) = line_count( itab[ id = 1 ] ). " In expression
" Check if exists
IF line_exists( itab[ id = 1 ] ).
...
ENDIF.
" Get index
DATA(idx) = line_index( itab[ name = 'Test' ] ).
" Table aggregations (with REDUCE)
DATA(sum) = REDUCE i( INIT s = 0 FOR wa IN itab NEXT s = s + wa-amount ).
DATA(min) = REDUCE i( INIT m = 999999 FOR wa IN itab
NEXT m = COND #( WHEN wa-val < m THEN wa-val ELSE m ) ).FILTER Expression
" Basic filter
DATA(filtered) = FILTER #( itab WHERE status = 'A' ).
" Using secondary key (more efficient)
DATA(filtered) = FILTER #( itab USING KEY by_status WHERE status = 'A' ).
" With EXCEPT (exclude matching lines)
DATA(non_active) = FILTER #( itab EXCEPT WHERE status = 'A' ).
" Filter with IN condition
DATA filter_values TYPE SORTED TABLE OF string WITH UNIQUE KEY table_line.
filter_values = VALUE #( ( `A` ) ( `B` ) ( `C` ) ).
DATA(matched) = FILTER #( itab IN filter_values WHERE status = table_line ).Group Processing
" Group by single field
LOOP AT itab INTO wa GROUP BY wa-category.
DATA(group_key) = wa-category.
LOOP AT GROUP wa INTO DATA(member).
" Process group members
ENDLOOP.
ENDLOOP.
" Group by multiple fields
LOOP AT itab INTO wa GROUP BY ( cat = wa-category
year = wa-year )
ASCENDING
ASSIGNING FIELD-SYMBOL(<grp>).
" <grp> contains group key fields
LOOP AT GROUP <grp> ASSIGNING FIELD-SYMBOL(<member>).
" Process member
ENDLOOP.
ENDLOOP.
" With aggregation (group size, index)
LOOP AT itab INTO wa GROUP BY ( category = wa-category
size = GROUP SIZE
index = GROUP INDEX )
ASSIGNING FIELD-SYMBOL(<grp>).
" <grp>-size contains number of entries in group
" <grp>-index contains group number (1, 2, 3...)
ENDLOOP.
" Without members (aggregate only)
LOOP AT itab INTO wa GROUP BY wa-category WITHOUT MEMBERS.
" Only process unique group keys
ENDLOOP.Secondary Table Keys
" Declaration
TYPES itab_type TYPE TABLE OF struc
WITH EMPTY KEY
WITH NON-UNIQUE SORTED KEY by_name COMPONENTS name
WITH UNIQUE HASHED KEY by_id COMPONENTS id.
" Using in READ
READ TABLE itab WITH KEY by_name COMPONENTS name = 'Test' INTO wa.
READ TABLE itab USING KEY by_id INTO wa WITH KEY by_id COMPONENTS id = 1.
" Using in LOOP
LOOP AT itab USING KEY by_name WHERE name CS 'test'.
...
ENDLOOP.
" Using in DELETE
DELETE itab USING KEY by_id WHERE id = 0.
" Key specification in expressions
DATA(line) = itab[ KEY by_name name = 'Test' ].
DATA(idx) = line_index( itab[ KEY by_name name = 'Test' ] ).Performance Considerations
Choose appropriate table type
- Standard: Sequential access, small tables, need index access
- Sorted: Frequent key access, range queries, need both index and key
- Hashed: Large tables with unique key access only
Use field symbols instead of work areas for modification in loops
Use secondary keys for different access patterns instead of SORT
Avoid dynamic WHERE in production-critical code
Use FILTER with key for efficient filtering
For large tables, prefer hashed/sorted over standard with BINARY SEARCH
DELETE ADJACENT DUPLICATES requires prior sort or sorted table