Thread: Noob question about types and lists

Hi,
i'm really new to postgres and have some doubts.
Hope somebody could explain.

Let say i have a table of "clients" and every client has a small number
of addresses. (let say 3)
My approch is to create a type "address" like this (simplified)

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?

Please forgive me if this is explained somewhere in the doc or in faqs,I
didn't find it.

Thank You

Christian

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

On gio, 2005-10-06 at 12:20 +0100, Richard Huxton wrote:

>  From the manuals...
> 

I didn't search very well.Sorry!

> 
> 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 [cut]

I wanted to use a different approch because addresses don't make any
sense for other tables and because they are typically few (3,4) and i
wanted to avoid making a join for this task... 
however.. i will use your approch.

Thank you for patience and suggestion!
Regards

Chris

xchris wrote:
> On gio, 2005-10-06 at 12:20 +0100, Richard Huxton wrote:
> 
>> From the manuals...
> 
> I didn't search very well.Sorry!

Easy enough to miss.

>>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 [cut]
> 
> 
> I wanted to use a different approch because addresses don't make any
> sense for other tables and because they are typically few (3,4) and i
> wanted to avoid making a join for this task... 
> however.. i will use your approch.

If you're using a relational DB, better get used to joins :-)
--   Richard Huxton  Archonet Ltd