Foreign key to multiple tables ???

Hi,

Suppose I want to create three tables: one "child" table and two master tables:

create table customer_account (customer_id number(9),

                               account_class varchar2(10),
                               account_type number(2),
                               ...)

create table savings_account_types(account_type number(2),


                                   ...)


create table check_account_types (account_type number(2),


                                   ...)

In the child table customer_account field account_class implies whether account_type refers to savings_account_types (account_class='savings') or check_account_types (account_class='check').

Is there an elegant way to create declarative data integrity constraints to make sure that every account has a valid account_class/account_type combination?

This functionality could be achieved using database triggers, but I suppose triggers won't fire during database import.

How about performance issues ?

Thanks,

Kirmo.Uusitalo_at_comptel.fi               Comptel Oy
System Analyst                          Ruoholahdenkatu 4
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