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help / color / mirror / Atom feedFrom: Ron <ronljohnsonjr@gmail.com>
To: pgsql-admin@lists.postgresql.org
Subject: Re: How do I alter an existing column and add a foreign key which is a Primary key to a table?
Date: Sat, 20 Jul 2019 20:25:33 -0500
Message-ID: <24840698-956d-31fe-96dd-9e9427890e39@gmail.com> (raw)
In-Reply-To: <820008379.2579287.1563670685484@mail.yahoo.com>
References: <820008379.2579287.1563670685484@mail.yahoo.com>
On 7/20/19 7:58 PM, Karen Goh wrote:
> Hi all,
>
> I used to write a script in MYSQL and foreign and primary key will be created.
>
> With PG4Admin, I am lost.
>
> I realised now that the keys are not created and perhaps that is why the join query is not working out.
>
> Please let me know what is the correct way to alter a column in a table to have foreign key to a tutor_id which is also the primary key of that table.
>
> So, meaning I need to create a foreign key as well as primary key for tutor_id.
>
> So far, this is what I have attempted but it is not working.
> ALTER TABLE tutor_subject
> ADD CONSTRAINT tutor_subject_pk
> PRIMARY KEY (tutor_id)
> ADD CONSTRAINT tutor_subject_fk
> FOREIGN KEY (tutor_id)
What error message do you get?
Does tutor_id already exist in tutor_subject?
What foreign table are you referencing? (I don't see that referenced in
your example.)
Have you read the documentation?
https://www.postgresql.org/docs/9.6/sql-altertable.html
http://www.postgresqltutorial.com/postgresql-primary-key/
http://www.postgresqltutorial.com/postgresql-foreign-key/
--
Angular momentum makes the world go 'round.
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Subject: Re: How do I alter an existing column and add a foreign key which is a Primary key to a table?
In-Reply-To: <24840698-956d-31fe-96dd-9e9427890e39@gmail.com>
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