Append Structures

Append Structures

Append structures are used for enhancements which are not in the standard, for example special developments, country versions and appending customer fields to tables.

An append structure is a structure which is assigned to exactly one table, but there may be several append structures for one table.

When a table is activated, all the append structures of the table are searched and the fields in these append structures are added to the table. If an append structure is created or changed, the table assigned to it is also adjusted to these changes when the append structure is activated.

Since the order of the fields in the ABAP Dictionary can differ from the order of the fields on the database, adding append structures or inserting fields in such append structures does not result in a table conversion.

The customer creates append structures in the customer namespace. The append structure is thus protected against overwriting during an upgrade. The fields in the append structure should also reside in the customer namespace, that is the field names should begin with ZZ or YY. This prevents name conflicts with fields inserted in the table by SAP.

The new versions of the standard tables are imported after an upgrade and the fields contained in the append structures are added to the new standard tables at activation.

Standard table TAB contains fields F1, F2 and F3. An append structure APP containing fields ZZ1 and ZZ2 is defined for this table. After activation of table TAB, the runtime object and database table belonging to TAB contain fields F1, F2, F3, ZZ1 and ZZ2. ‘.append APP’ is displayed in the ABAP Dictionary as the last line in the field display of table TAB.

Further Remarks:

An append structure can only be assigned to exactly one table. If you want to append the same fields to several tables, you can store the fields in a structure. In this case you must create an append structure for each of these tables and include the structure there.

If you want to insert a field which is to be delivered with the R/3 standard in the next Release in the customer system in advance, you must include it in the table itself as a repair. If you include such a field in an append structure for the table, it will occur twice when the new standard table is imported, resulting in an activation error.

No append structures may appended to tables with long fields (data type VARC, LCHR or LRAW) since a long field must always be the last field of the table. However, structures with long fields can be enhanced with append structures.

If a table with an append structure is copied, the fields of the append structure become fields of the target table.

Foreign keys for the appended fields must be defined within the append structure. Fields of the table assigned to the append structure may be defined when assigning the key field and foreign key field.

Indexes on the appended fields must be defined in the original table.

See also:

Adding Append Structures