Before release 3.0 internal tables were declared as shown below.
DATA: BEGIN OF <int_tab> OCCURS <n>,
END OF <int_tab>.
Hashed Tables, Sorted Tables and Key access were introduced only in release 4.0. Standard tables existed before release 3.0, they all had a header line and a flat-structure line type. In release 4.0 the above syntax is still supported, the new syntax is as follows.
TYPES: BEGIN OF <int_tab>,
END OF <int_tab>.
DATA <int_tab> TYPE STANDARD TABLE OF <int_tab> WITH NON-UNIQUE DEFAULT KEY INITIAL SIZE <n> WITH HEADER LINE.
The header line addition works as a work area. Basically it is an additional data object with the same name and line type as the internal table. Using an Internal table with header line does lead to a confusion as the internal table and the header line share the same name. Hence in the code if data is to be moved to the body of the internal table and not to the header line then the table needs to be referred as int_tab[]. It is a therefore good practice NOT TO USE a header line for an internal table. It is better to declare a separate work area.
In the current version WITH HEADER LINE addition is obsolete; and hence it should not be used.
DATA: BEGIN OF int_tab OCCURS 0, vbeln like vbak-vbeln, matnr like mara-matnr, END OF int_tab.
Old way of declaring an internal table. Here the OCCURS 0 is the same as INTIAL SIZE <n>
* Types Declaration TYPES: BEGIN OF ty_ord, vbeln like vbak-vbeln, matna like mara-matnr, END OF ty_ord.
New way. Declare TYPES first.
* Work Area Declaration DATA wa_ord TYPE ty_ord.
Declare a WORK AREA, this is useful in terms of passing data to the internal table.
TYPES itab TYPE STANDARD TABLE OF ty_ord.
Declaration of table type itab.
* Internal Table Declaration Data int_ord TYPE STANDARD TABLE OF ty_ord.
Declaration of the actual INTERNAL TABLE
Sample Code for ABAP INTERNAL TABLE DECLARATION.
* Types Declaration TYPES: BEGIN OF ty_ord, vbeln like vbak-vbeln, matna like mara-matnr, END OF ty_ord.
* Work Area Declaration DATA wa_ord TYPE ty_ord.
TYPES itab TYPE STANDARD TABLE OF ty_ord.
* Internal Table Declaration Data int_ord TYPE itab.
move: '0000123456' to wa_ord-vbeln.
append wa_ord to int_ord.
move: '0000123457' to wa_ord-vbeln. append wa_ord to int_ord.
Always use Pretty Printer and Extended Program Check before releasing the code.
Do not leave unused code in the program. Comment the code thoroughly. Align the comments and the Code. Follow the SAP Standards and SAP Best Practices guidelines. It’s a good practice to take a dump of the code on your local drive.
