ABAP Keyword Documentation →  ABAP − Reference →  Processing Internal Data →  Internal Tables →  Processing Statements for Internal Tables → 

LOOP AT itab  Syntax Diagram

Short Reference

Syntax

LOOP AT itab result [cond].
  ...
ENDLOOP.

Effect

The LOOP and ENDLOOP statements define a loop around a statement block. The statement LOOP reads rows from the internal table itab sequentially. itab is a functional operand position.

The statement block between LOOP and ENDLOOP is executed once for each row. To exit processing of the statement block, the statements described in the leave loops section can be used.

If the internal table is specified as the return value or result of a functional method, a constructor expression, or a table expression, the value is persisted for the duration of the loop. Afterwards, it is no longer possible to access the internal table.

If no explicit table key name is specified after USING KEY, the order in which the rows are read depends on the table type as follows:

The loop continues to run until all the table rows that meet the cond condition have been read or until it is exited with a statement. If no appropriate rows are found or if the internal table is blank, the loop is not run at all.

System Fields

During each loop run for index tables, and when using a sorted key, the statement LOOP AT sets the value of the system field sy-tabix to the row number of the current row in the relevant table index. In hashed tables and when using a hash key sy-tabix is set to the value 0. LOOP AT does not modify sy-subrc. After leaving the loop using ENDLOOP, sy-tabix is set to the value that it had before entering the loop and that applies for sy-subrc:

sy-subrc Meaning
0 The loop was run at least once.
4 The loop was not run at all.

The system fields sy-tfill and sy-tleng are also filled.

Changing internal tables in a loop

If rows are inserted or deleted in the statement block of a LOOP, this has the following effects: The position of inserted or deleted rows with regard to the current row is determined by the row numbers in the corresponding table index in the case of loops on index tables or if using a sorted key. In the case of loops on hashed tables and if using a hash key, the position depends on the insert order.

The replacement of the entire table body in a LOOP using this table causes the loop to be exited at the next loop pass in accordance with the rules described above. This is particularly the case if new rows were added to the table afterwards. Since this usually produces unpredictable program behavior, the entire table body cannot be accessed in change mode in a loop. If this is statically discernible, a syntax error occurs in classes and for LOOPS with statically discernible secondary keys. Otherwise, the syntax check simply returns a warning for compatibility reasons. However, at runtime, a runtime error always occurs in the case of the replacement of the entire table body with statements such as CLEAR, FREE, LOCAL, REFRESH, SORT, DELETE ... WHERE, and with all types of assignments to itab.

Programming Guideline

Loop Processing

Notes

Example

Loop across an internal table constructed using the value operator VALUE, where each row is assigned to a field symbol declared inline using FIELD-SYMBOL.

TYPES t_itab TYPE TABLE OF i WITH EMPTY KEY.

LOOP AT VALUE t_itab( ( 1 ) ( 2 ) ( 3 ) ) ASSIGNING FIELD-SYMBOL(<fs>).
  cl_demo_output=>write( |{ <fs> }| ).
ENDLOOP.
cl_demo_output=>display( ).

Example

Nested LOOPs without an explicitly specified key. The contents of the current row for the outer loop are analyzed in the WHERE condition for the inner loop.

PARAMETERS p_name TYPE scarr-carrname DEFAULT '*'.

DATA: scarr_tab TYPE SORTED TABLE OF scarr
                WITH UNIQUE KEY carrname,
      spfli_tab TYPE SORTED TABLE OF spfli
                WITH NON-UNIQUE KEY carrid.

FIELD-SYMBOLS <scarr_line> LIKE LINE OF scarr_tab.
DATA spfli_line LIKE LINE OF spfli_tab.

SELECT *
       FROM scarr
       INTO TABLE scarr_tab.

SELECT *
       FROM spfli
       INTO TABLE spfli_tab.

LOOP AT scarr_tab ASSIGNING <scarr_line>
                  WHERE carrname CP p_name.
  LOOP AT spfli_tab INTO spfli_line
                    WHERE carrid = <scarr_line>-carrid.
    cl_demo_output=>write_data( spfli_line ).
  ENDLOOP.
ENDLOOP.
cl_demo_output=>display( ).

Exceptions

Catchable Exceptions

CX_SY_ITAB_DYN_LOOP

Non-Catchable Exceptions




Continue
LOOP AT itab - result
LOOP AT itab - cond
ENDLOOP
Internal Tables, Loop with Key Specified