Can a field from primary key be used as a foreign key in the same table?

Question

I have a table T1 with 4 fields (F1, F2, F3 and F4) together acting as unique identifier of the table rows. Can one of these fields (F4 say) be used as a foreign key for the same table? We already have master data table (T2) for the same.

Answer 1

Yes, it can.

You can easily set one of the primary key fields as a foreign key and assign it a check table. By default SAP proposes you domain value table of this field as a check table for it.

Moreover, while creating you can specify the role of a foreign key field in your T1 table: either it is key or non-key.

The only limitation: you cannot create foreign key for a field if it's already assigned the same value table in its domain as current. For example, one cannot make field MATNR in MARA foreign key, because it has value table MARA in its domain. You'll get an error E2165:

Check table of the domain is current table (FK maintenance not possible)