Re: very basic question - Mailing list pgsql-general

From Arjen van der Meijden
Subject Re: very basic question
Date
Msg-id 004001c2c95a$4df3fb30$3ac15e91@acm
Whole thread Raw
In response to very basic question  (Dennis Gearon <gearond@cvc.net>)
List pgsql-general
You could simply do something like this:

INSERT INTO Usrs (login, gen_id) VALUES ('foo', (SELECT gen_id FROM Gens
WHERE gen = '$gen'));

It will even fail with a nice error if there won't be an id to select :)

Regards,

Arjen

> -----Oorspronkelijk bericht-----
> Van: pgsql-general-owner@postgresql.org
> [mailto:pgsql-general-owner@postgresql.org] Namens Dennis Gearon
> Verzonden: vrijdag 31 januari 2003 19:47
> Aan: pgsql-general@postgresql.org
> Onderwerp: [GENERAL] very basic question
>
>
> If I have the following two tables, (very much shortened for
> your convenience):
>
> CREATE TABLE Gens(
> gen_id serial NOT NULL CONSTRAINT PK_Gens1 PRIMARY KEY,
> gen varchar(16) DEFAULT 'none' NOT NULL, --
> CONSTRAINT UC_Gens1 UNIQUE(gen));
> COMMENT ON COLUMN Gens.gen_id IS 'integer surr primary key';
> COMMENT ON COLUMN Gens.gen IS 'examples are JR, SR, I, III, etc';
>
> CREATE TABLE Usrs(
> usr_id serial NOT NULL CONSTRAINT PK_Usrs1 PRIMARY KEY,
> login varchar(32) NOT NULL,
> gen_id int4 NOT NULL,
> CONSTRAINT FK_A_Usr_Has_A_Generation_2 FOREIGN KEY (gen_id)
> REFERENCES Gens (gen_id), CONSTRAINT UC_Usrs1 UNIQUE(login));
> COMMENT ON COLUMN Usrs.usr_id IS 'integer surr primary key';
>
>
> How do I insert values into Usrs that use the values of
> Gens.gen_id for referential integrity,
> but by referencing the Gen.gen field?
>
> Say I wanted to insert (in one statement):
>     'fancy_login_name' for Usrs.login
>         *and*
>     the Gen.gen_id for 'JR' in Usrs.gen_id
>         *assuming*
>     that 'JR' exists in Gen.gen.
>
> Thank you very much. In MySQL I would have used PHP to find
> the Gen.gen_id and then inserted
> that, (whether that was the right way, I don't know)
>
> OK, I'm a newbie to USING databases, I'm fair at designing
> them, I think.
>
>
>
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