Question

I just have a quick question about notation. I have two tables right now.

This one has basic animal information:

 create table d_animals (
  an_id     integer     primary key
, an_gender varchar2(1) not null
, an_dob    date        not null
, an_name   varchar2(10)    not null
);

This one is about cats:

 create table d_cats (
       an_id                        integer     primary key
     , feline_leukemia_test_date    date        not null
     , an_id    foreign key references d_animals_(an_id)
     );

As you can see, I’m trying to use an_id as the primary key in d_cats but also refernce the an_id from the d_animals table. I’m getting the following error for d_cats:

 ORA-00957: duplicate column name

So how do I correctly write this?

Also, I don’t want to create another column for d_cats. My professor wants us to write d_cats with only an_id and feline_leukemia_test_Date.
Thanks.

Answer 1

Use a named constraint, i.e.:

create table d_cats (
   an_id                        integer     primary key
 , feline_leukemia_test_date    date        not null
 , constraint d_cats_animals_fk foreign key (an_id) references d_animals (an_id)
 );