Thread: Table inheritance problem

Gianvito Pio schrieb:
> Hello,
> I have 3 tables: persons, operators and persons_position.
>  
> This is a semplified examples of their structures:
>  
> CREATE TABLE persons
> (id varchar NOT NULL,
> CONSTRAINT "PK_Persons" PRIMARY KEY(id));
>  
>  
> CREATE TABLE operators
> (id varchar NOT NULL,
> CONSTRAINT "PK_Operators" PRIMARY KEY(id))
> INHERITS(persons);
>  
> CREATE TABLE persons_position
> (id bigserial NOT NULL,
> person varchar NOT NULL);
>  
> and then there is a FOREIGN KEY CONSTRAINT from persons_position.person 
> TO persons.id.
>  
> If I insert a tuple in operators...it results also in persons, but when 
> I insert a tuple in persons_position, it says me I have violated the 
> foreing key constraints. So it appears that the tuple really ISN'T in 
> the persons table and the foreing key check fails.
>  
> How could I solve it, keeping the inheritance there?
> Thanks

Hi,

sure it does throw that error. Your foreign key constraint is wrong. The check will look 
like this:

test=# insert into persons_position values(2,'andy');
ERROR:  insert or update on table "persons_position" violates foreign key constraint 
"persons_position_persons_fkey"
DETAIL:  Key (person)=(andy) is not present in table "persons".

You could solve it by altering the table persons:

test=# alter table persons add column person varchar(255);
ALTER TABLE
test=# insert into persons_position values(2,'andy'); 

INSERT 0 1

Or change the foreign key constraint in persons_position to id (be careful - the datatypes 
are different)

Cheers

Andy