APPEND STRUCTURE

APPEND STRUCTURE:

Append structures permit you to append customer fields to a SAP standard table without having to modify the table definition.

An append structure is a structure which is assigned to exactly one table. There can be several append structures for a table.

When a table is activated, all the active append structures for the table are found and their fields are appended to the table. If an append structure is created or changed, the table to which it is assigned is also activated and the changes also take effect there when it is activated.

Like all structures, an append structure defines a type that can be used in ABAP programs.

With Release 4.6C you can define foreign keys for fields that already exist in the table using an append structure. Search helps can also be attached to fields that already exist in the table.

Customers create append structures in their namespace. The append structures are thus protected against overwriting during an upgrade.

The new versions of the standard tables are imported during the upgrade. When the standard tables are activated, the fields contained in the active append structures are appended to the new standard tables. When append structures are added to a table, you therefore do not have to manually adjust the customer modifications to the new SAP version of the table (Transaction SPDD) during the upgrade.


The order of the fields in the ABAP Dictionary can differ from the order of the fields in the database. You therefore do not have to convert the table when you add an append structure or insert fields in an existing append structure. The new fields are simply appended to the table in the database. You can always adjust the structure by adjusting the database catalog (ALTER TABLE).


The new version of the SAP standard table is activated and the new field is appended to the database table.

Please note the following points about append structures:

No append structures may be created for pooled and cluster tables.

If a long field (data type LCHR or LRAW) occurs in a table, it cannot be extended with append structures. This is because such long fields must always be in the last position of the field list, i.e. they must be the last field of the table.

If you as a customer add an append structure to an SAP table, the fields in this append structure should be in the customer namespace for fields, that is they should begin with YY or ZZ. This prevents name collisions with new fields inserted in the standard table by SAP.

If you as a partner have your own reserved namespace for your developments, the fields you select in append structures should always lie in this namespace.

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