One of the ways of enhancing SAP standard transparent tables & structures is through Append Structure. In this post, we will plunge into the concept and usage of Append Structure.
Append Structure is used to add new customer fields to SAP Standard tables and structures without undergoing a modification. Other than its creation process and some special properties, it can be treated exactly similar to normal include structures in programs.
So, lets dive to see how does Append Structure technique works?
How does SAP creates an Enhancement Provision?
SAP Application Developers make an enhancement provision in standard transparent table or structure by setting Enhancement Category attribute in the table/structure. Using the value of ‘Enhancement Category’ attribute, SAP controls the extent to which a table / structure is allowed to be enhanced.
Attribute ‘Enhancement Category’ can take one of the following values:
- Can be enhanced (deep) – Fields of any data type (includes tabletypes, object references and strings) can be added to the table/ structure.
- Can be enhanced (character-type or numeric) – Fields of any data type except tabletypes, object references and strings can be added to the table/ structure.
- Can be enhanced (character-type) - Only character type fields (data type C, N, D, or T) can be added to tables / structures.
- Cannot be enhanced – Customers are not allowed to add any fields.
Enhancement category of a table/structure can be accessed by following the below mentioned steps:
- Go to transaction SE11 & display the specific table / structure.
- Navigate in the menu bar to ‘Extras -> Enhancement Category’ to find assigned enhancement category.
How does Customer creates an Append Structure to add new fields?
Customers create Append Structures to add their fields in the following manner:
- Go to transaction SE11 and display the table / structure to be enhanced.
- Press the button ‘Append Structure’ in the application toolbar.
- Enter the name of the ‘Append Structure’.
- Add the customer fields.
- Save & activate the append structure and go back to original table / structure to find the newly added fields.
What Naming Convention is used in Append Structures?
Append Structures & their fields are named in customer namespace in order to avoid conflicts e.g. SAP adding new fields with the same name in future releases, during SAP upgrades.
Append Structures follow the naming pattern as Z* or Y*. (Note: Underscores ‘_’ are not allowed in the name at 2nd & 3rd character.)
Fields of append structures follow the naming pattern as ZZ* or YY*.
Some Prerequisites:
- The table to be enhanced should not be a pool or cluster table.
- The enhancement category of the table / structure should allow adding customer fields i.e. Enhancement category should not be set to ‘Cannot be enhanced’. Moreover, even if the enhancements are allowed, the newly added customer fields should be in accordance with the enhancement category of table / structure.
- In case of tables, it’s not allowed to create append structure if the table contains long fields (i.e. fields with data type VARC, LCHR, LRAW). However, it’s allowed in case of structures.
Salient Features:
- Append structures appear in original table / structure with .APPEND key word.
- An append structure can be used exactly for one table or structure. However, it’s possible to add more than one append structures to one table or structure.
- When an append structure is changed and activated, the original table / structure also gets activated automatically.
- The append structure can be used in programs exactly similar to the way fields of a normal structure is used.
- When a table / structure containing append structure is copied, the target table / structure contains the fields in append structures as normal fields.
