Internal tables are a core concept for storing structured data. You can create them dynamically at runtime using RTTS (Runtime Type Services).

DATA: lo_descr TYPE REF TO cl_abap_structdescr,
lo_table TYPE REF TO cl_abap_tabledescr,
lr_data TYPE REF TO data,
lr_line TYPE REF TO data.

“— Step 1: Define a structure dynamically
lo_descr = cl_abap_structdescr=>create(
VALUE #( ( name = ‘FIELD1’ type = cl_abap_elemdescr=>get_c( 10 ) )
( name = ‘FIELD2’ type = cl_abap_elemdescr=>get_i( ) ) )
).

“— Step 2: Create internal table description
lo_table = cl_abap_tabledescr=>create( lo_descr ).

“— Step 3: Create actual data object (the table)
CREATE DATA lr_data TYPE HANDLE lo_table.
ASSIGN lr_data->* TO FIELD-SYMBOL(<itab>).

“— Step 4: Create a line type and assign
CREATE DATA lr_line TYPE HANDLE lo_descr.
ASSIGN lr_line->* TO FIELD-SYMBOL(<wa>).

“— Step 5: Fill dynamically created table
<wa>-field1 = ‘Hello’.
<wa>-field2 = 123.
APPEND <wa> TO <itab>.

<wa>-field1 = ‘World’.
<wa>-field2 = 456.
APPEND <wa> TO <itab>.

“— Step 6: Loop through the dynamic internal table
LOOP AT <itab> ASSIGNING <wa>.
WRITE: / <wa>-field1, <wa>-field2.
ENDLOOP.

Key Points:

1. Use RTTS (Runtime Type Services) → cl_abap_structdescr, cl_abap_tabledescr, cl_abap_elemdescr.
2. Create data objects at runtime with CREATE DATA ... TYPE HANDLE.
3. Use field symbols (<itab>, <wa>) to access the data.