Re: Noob question about types and lists - Mailing list pgsql-sql

From Richard Huxton
Subject Re: Noob question about types and lists
Date
Msg-id 4345088E.4090001@archonet.com
Whole thread Raw
In response to Noob question about types and lists  (xchris <lyralyra@fastmail.fm>)
Responses Re: Noob question about types and lists
List pgsql-sql
xchris wrote:
> CREATE TYPE address AS
> (
>         street          VARCHAR(160),
>         city            INTEGER,
>         cap             INTEGER,
>         country         INTEGER  (those are referring to other table)
> );
> 
> and then composing table client
> 
> CREATE TABLE client
> (
>         id              SERIAL PRIMARY KEY,
>         name            VARCHAR(80),
>         surname         VARCHAR(80),
>         address         address[3]
>     ....
>         UNIQUE (name,surname)
> );
> 
> 
> This doesn't work.
> I cannot create a list of types.
> 
> I'm using a wrong syntax? or simply i cannot do this?
From the manuals...

8.10. Arrays
PostgreSQL allows columns of a table to be defined as variable-length 
multidimensional arrays. Arrays of any built-in or user-defined base 
type can be created. (Arrays of composite types or domains are not yet 
supported, however.)

So - you can't do this at the moment.

However - I don't think you want to anyway. If you're going to use a 
relational database, try a relational approach! Typically, you would do 
something like:

CREATE TABLE client  (id ..., name ...)
CREATE TABLE address (id ..., street ...)
CREATE TABLE client_address (client_id ..., address_id ...)

Then, you can add some foreign-key constraints so PG makes sure that the 
ID numbers in client_address are all valid.

This makes it simple to get client names, client addresses or both together.

HTH
--  Richard Huxton  Archonet Ltd


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