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From: Samuel Marks <samuelmarks@gmail.com>
Date: Tue, 23 Sep 2025 23:19:33 -0500
Message-ID: <CAMfPbcbuww3geDUFce+eQ2DEtg1n=qHQ3N=2LdZYdJ55cUUHBA@mail.gmail.com>
Subject: Re: How do I upsert depending on a second table?
To: Juan Rodrigo Alejandro Burgos Mella <rodrigoburgosmella@gmail.com>
Cc: pgsql-general@lists.postgresql.org
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Precedence: bulk

Ok so you're thinking I give up on putting it all in one query and
instead use a transaction? - Is that the recommended way?

```sql
TRUNCATE repo, org;
INSERT INTO org(name, owner) VALUES ('org0', 'user0');
```

```sql
START TRANSACTION READ WRITE;

SELECT 1/COUNT(*)
FROM org
WHERE name =3D 'org0'
  AND owner =3D 'wrong user';

INSERT INTO repo (id, full_name, org)
VALUES (0, 'org0/name0 by wrong user', 'org0')
ON CONFLICT (full_name) DO UPDATE
    SET full_name =3D EXCLUDED.full_name,
        org       =3D EXCLUDED.org
RETURNING id;

COMMIT;
```


On Tue, Sep 23, 2025 at 7:25=E2=80=AFPM Juan Rodrigo Alejandro Burgos Mella
<rodrigoburgosmella@gmail.com> wrote:
>
> Hi Samuel
>
> Using ON CONFLICT is a headache.
> It's better to use the versatility of a Trigger: you have the full record=
 at your fingertips, and if you're going to UPDATE, you have the previous r=
ecord too.
> There's much more control.
>
> Also, you can always count on the beloved foreign keys, which are also qu=
ite useful.
>
> Atte.
> JRBM
>
>
> El mar, 23 sept 2025 a las 15:37, Samuel Marks (<samuelmarks@gmail.com>) =
escribi=C3=B3:
>>
>> Attempt:
>> ```sql
>> CREATE TABLE org
>> (
>>     "name"      VARCHAR(50) PRIMARY KEY,
>>     owner       VARCHAR(50) NOT NULL
>> );
>>
>> CREATE TABLE repo
>> (
>>     "id"           INTEGER PRIMARY KEY,
>>     full_name      VARCHAR(255) UNIQUE NOT NULL,
>>     org            VARCHAR(50)         NOT NULL REFERENCES org ("name")
>> );
>>
>> INSERT INTO org(name, owner) VALUES ('org0', 'user0');
>>
>> INSERT INTO repo (id, full_name, org)
>> VALUES (0, 'org0/name0 by wrong user', 'org0')
>> ON CONFLICT (full_name) DO UPDATE
>>     SET full_name =3D EXCLUDED.full_name,
>>         org       =3D EXCLUDED.org
>> WHERE EXISTS (SELECT 1
>>               FROM org org_tbl
>>               WHERE org_tbl.name =3D EXCLUDED.org
>>                 AND org_tbl.owner =3D 'wrong user')
>> RETURNING *;
>>
>> SELECT * FROM repo WHERE id =3D 0;
>> ```
>>
>> This all succeeds. It should fail because the 'wrong user' is trying
>> to create a new=E2=80=94or update an existing=E2=80=94repo.
>>
>> Thanks for all suggestions
>>
>>