Using a function in a check constraint

Question

Hi,
I created a domain table(id, code, domain_code, description) and foreign keys to this table. To ensure that a valid domain is put in the column I created a function that returns a boolean and has two parameters (id and domain_code). It returns true if the id and domain belong together.
I want to know if it is possible to create a check constraint which validates the data in the refering table with the data in the domain table.
Does anyone know if this is possible? Or do I have to use a db-trigger?
Regards,
Romano

Answer 1

It still sounds like all you need is a foreign key constraint. Please see the example below, based on your revised criteria.
scott@ORA92> create table domain
  2    (id         number,
  3       code         number,
  4       domain_code number,
  5       constraint  domain_pk primary key (id),
  6       constraint  domain_uk unique (code, domain_code))
  7  /
Table created.
scott@ORA92> insert into domain values (1, 10, 2)
  2  /
1 row created.
scott@ORA92> create table domain_values_table
  2    (id         number,
  3       domain_code number,
  4       constraint domain_values_table_uk unique (id, domain_code))
  5  /
Table created.
scott@ORA92> insert into domain_values_table values (1, 2)
  2  /
1 row created.
scott@ORA92> commit
  2  /
Commit complete.
scott@ORA92> create table referring
  2    (id         number,
  3       domain_code number,
  4       status         number,
  5       constraint  referring_fk foreign key (status)
  6                references domain (id),
  7       constraint  referring_fk2 foreign key (id, domain_code)
  8                references domain_values_table (id, domain_code))
  9  /
Table created.
scott@ORA92> insert into referring values (1,  2, null)
  2  /
1 row created.
scott@ORA92> insert into referring values (3, 4, null)
  2  /
insert into referring values (3, 4, null)
ERROR at line 1:
ORA-02291: integrity constraint (SCOTT.REFERRING_FK2) violated - parent key not found