From: | Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com> |
---|---|
To: | Yan Cheng Cheok <yccheok(at)yahoo(dot)com> |
Cc: | pgsql-general(at)postgresql(dot)org |
Subject: | Re: Is there any different for foreign key to be serial instead of integer |
Date: | 2010-01-07 04:07:45 |
Message-ID: | dcc563d11001062007n4f3657ffrf89fd0eb4b0c8b7d@mail.gmail.com |
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Lists: | pgsql-general |
On Wed, Jan 6, 2010 at 8:51 PM, Yan Cheng Cheok <yccheok(at)yahoo(dot)com> wrote:
> I came across a lot of similar example for foreign key
>
> CREATE TABLE orderinfo
> (
> orderinfo_id serial ,
> customer_id integer NOT NULL,
> date_placed date NOT NULL,
> date_shipped date ,
> shipping numeric(7,2) ,
> CONSTRAINT orderinfo_pk PRIMARY KEY(orderinfo_id),
> CONSTRAINT orderinfo_customer_id_fk FOREIGN KEY(customer_id) REFERENCES
> customer(customer_id)
> );
>
> instead of let customer_id being type as integer, can i let it be serial? is there any difference?
>
> if the table referenced by customer_id is having primary key typed big serial, customer_id shall be declared as bigint ?
serial and big serial are basically syntactic sugar for creating the
table with an int / bigint, create a sequence, create a default for
the bigint field, and setting a dependency in the system catalogs for
the sequence to the table. So, yep, a serial / bigserial is
equivalent to int / bigint from an FK point of view.
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