Forigen Key constraints on nested table column:
What can I do to prevent a REF stored in a nested table becoming dangling? I tried using a forigen key constraint on nested table column but failed with (ORA-30730: referential constraint not allowed on nested table column). Why it is not allowed?
Unique for REF column:
My another question is why a REF column of a table cannot be unique/ used as a primary key (ORA-02329: column of datatype REF cannot be unique or a primary key)? I want to make sure that the same REF will not appear in the column twice. What can I do?