From: | Stephan Szabo <sszabo(at)megazone23(dot)bigpanda(dot)com> |
---|---|
To: | "William N(dot) Zanatta" <william(at)veritel(dot)com(dot)br> |
Cc: | <pgsql-general(at)postgresql(dot)org> |
Subject: | Re: Help with Arrays and References |
Date: | 2002-06-25 00:25:43 |
Message-ID: | 20020624172038.P61359-100000@megazone23.bigpanda.com |
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Lists: | pgsql-general |
On Mon, 24 Jun 2002, William N. Zanatta wrote:
> Hi,
>
> I'm starting on PostgreSQL so please be patient; =]
>
> I'm building a book library database in which I have a table
> TBL_FORMAT which keeps basic information on various file-formats (ie 1,
> PDF, Portable Document Format) and a TBL_BOOKS which I want to reference
> TBL_FORMAT. But the column Format inside TBL_BOOKS is an array, as a
> book may exist in one or more file types. My doubt is: If I make
> something like
>
> CREATE TABLE "tbl_books" (
> "id_book" int4 DEFAULT nextval('TBL_Books_ID_Books_Seq'::text) NOT NULL,
> "format" _int4 NOT NULL REFERENCES TBL_Format ON_UPDATE CASCADE,
> ...
>
> will the CASCADE action update my TBL_Books (Format) keeping the
> other values in the array or will it erase all and set the new Format value?
That shouldn't even be legal assuming that tbl_format's key is an int.
The two types must be comparable which isn't true of int4 and _int4.
You're probably better off with a details table with the book's id and
format's id and appropriate references.
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