ABAP Keyword Documentation → ABAP - Dictionary → Classic Objects in ABAP Dictionary → Enhancements
Append Structures
An append structure is a structure in ABAP Dictionary appended to another structure or database table and which adds its components to this structure or table. In customer systems, append structures can be added to structures and database tables delivered by SAP. An append structure is assigned to exactly one table or structure. There can, however, be more than one append structure for a table or structure. The components of append structures must meet the prerequisites for table fields.
The following enhancements can be made to a database table or structure using an append structure:
- New components inserted (if permitted by the enhancement category)
- Foreign keys defined for existing fields of a database table
- Search helps bound to existing components
All enhancements are part of the append structure, which means that any changes made to these enhancements are made only using the append structure. The same applies to transports. When a database table or structure is activated, all associated append structures are found and their components are appended to the database table or structure. Any foreign keys or search help bindings added using the append structure are also appended. When an append structure is activated, the assigned database table or structure is adapted to the changes made. Any existing tables are not converted, which can put the fields in the dictionary in a different order from the order on the database. When a structure or database table with an append structure is copied, the appended fields, foreign keys, and search helps become real elements of the target of the copy.
The following must be noted when using append structures to enhance database tables:
- Append structures can only be appended to transparent tables.
- No append structures can be appended to database tables with fields of the type LCHR or LRAW, since these fields must always be the last field of the table.
- Any fields appended to a database table using an append structure can be added to its secondary indexes. No secondary index can be defined for the append structure itself.
- A binding of a check table or search help that already exists for a field of the database table cannot be modified using the append structure.
Enhancements of SAP structures or SAP tables using append structures in customer systems do not constitute modifications. Append structures created for SAP objects in customer systems are in the customer namespace (or in the namespace of a partner of a special development project) and hence are protected from being overwritten by upgrades. It is advisable to also create the components of append structures of this type with names from the customer namespace to avoid naming conflicts. After an upgrade, the associated append structures are again appended to tables modified by SAP.
Append structures can be defined as form-based structures in transaction SE11 or as source-code-based structures using Dictionary DDL in the ABAP Development Tools. The following section is a summary of the syntax of the source code-based definition:
Other versions:
7.31 | 7.40 | 7.54
Note
The same structure can be appended to multiple database tables or structures by including it in the individual append structures as an include structure.
Example
The append structure DEMO_APPEND_STRUCTURE enhances the structure DEMO_STRUCTURE.