Date: Sun, 1 Jun 2003 23:21:37 -0700
From: Sean Chittenden <sean@chittenden.org>
To: "Erik G. Burrows" <eburrows@erikburrows.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: SQL problem: bank account
Message-ID: <20030602062137.GD65470@perrin.int.nxad.com>
References: <1054531815.13212.27.camel@griffin.jedi-group.com>
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> It seems to me this is a simple problem, but the solution eludes me.
>
> I have a table:
> 
> bank_account (
>   transaction_id int not null serial,
>   customer_id int not null references customer(id),
>   ts timestamp not null default now(),
>   amount float not null,
>   balance float not null,
>   primary key(transaction_id)
> )
> 
> I need to get the most recent transaction for each customer. I need only
> the transaction ID, but the entire row would be best.

For the sake of being explicit, change your table definition (though
what you have above is a-okay and works):

CREATE SEQUENCE transaction_id_seq;
CREATE TABLE bank_account (
  transaction_id int not null DEFAULT NEXTVAL('transaction_id_seq'::TEXT),
  customer_id int not null references customer(id),
  ts timestamp not null default now(),
  amount float not null,
  balance float not null,
  primary key(transaction_id)
);

Once you insert a value into the bank_account table, SELECT
CURRVAL('transaction_id_seq') will be what you're looking for.  Read
up on CURRVAL() at:

http://www.postgresql.org/docs/view.php?version=7.3&idoc=1&file=functions-sequence.html

-sc

-- 
Sean Chittenden