Database-table default value for a column in SAP R/3

Question

In the context of my SAP Application I added a column to an existing table and would like to define a default value for it, so that old code working with the table (code that is inserting lines especially) doesn't have to care about the new column - rather I want it to be filled with a predefined default value automatically (only if no value is specified of course).

The DB-system that lies behind is an Oracle-DB, though I have only access to it through the SAP-GUI and the ABAP-SQL.

As our company expert for SAP did not know if this is possible I thought maybe someone here would. So - is this possible and if it is - how?

Edit - Requested Scenario details: The scenario is actually very simple: We have a users-table for our application containing the standard user stuff (name, some setting, Ids, division, a bunch of flags and so on), and I added a column to store a simple setting (the design the user has chosen for his webinterface). It contains simply a name (char 40). That's the column I talked about above and I want the default value for it to be let's say "Default Design".

Answer 1

Please, don't even think about doing this on a database level. Seriously. Changes made to the database layer directly will not be visible inside the system and lead to all kinds of strange side effects that will be a nightmare to support. Besides, your changes won't be picked up by the Change and Transport System - you'd have to update the QA and Production systems manually.

If possible, I'd recommend to choose your domain values in a way that the neutral field value (spaces, zero, whatever) corresponds to your default value. If this is not possible, please describe your scenario in detail to get a more specific answer.

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The SAP R/3 / ABAP environment does not give you the option of adding default values for a column. You can only choose to force the system to fill the non-NULL default values when adding a column, but this is usually a bad idea. It takes time to modify all the data and insert the default values, and depending on the table size and criticality, this can lead to a production outage. Filling the fields with default values has to be performed by the application server, not the database. In your case, I'd just add the logic in the read-access module, something like

IF my_user-ze_design IS INITIAL.
  my_user-ze_design = co_ze_default_design.
ENDIF.

Answer 2

You can define default values for columns added to tables - and if your DB is Oracle 11g (or later), Oracle introduced "Dictionary Only Add Column", which means the default value metadata is stored only in the dictionary - so existing records do not need to be updated with the default value and there is no overhead, no matter how large the table.