Date: Mon, 10 Dec 2007 12:08:48 +0100
From: "A. Kretschmer" <andreas.kretschmer@schollglas.com>
To: pgsql-sql@postgresql.org
Subject: Re: INSERT INTO relational tables
Message-ID: <20071210110848.GE917@a-kretschmer.de>
References: <20071207172528.820B92C96D4@maia-2.hub.org>
	<20071209075032.2A1112E3294@postgresql.org>
	<20071210104204.324340@gmx.net>
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am  Mon, dem 10.12.2007, um 11:42:04 +0100 mailte Stefan Scheidegger folgendes:
> Thanks for your hints so far.
> 
> I'm looking for both syntax simplicity and referential integrity. I'm
> using c++ with libpqxx, but I didn't find a good object-relational
> mapper. And I'm too lazy to implement a whole persistency layer as I
> don't have a huge DB with many relations.
> 
> I tried Andreas' suggestion with a RULE for INSERT on a VIEW. I
> created the VIEW composing my table with customers and orders:
> 
> CREATE VIEW vw_customer_insert AS SELECT * FROM tbl_customer,
> tbl_order WHERE cust_id = ord_customer;
> 
> Then I added a rule for the inserting: CREATE RULE rl_customer_insert
> AS ON INSERT TO vw_customer_insert DO INSTEAD ( INSERT INTO
> tbl_customer VALUES (DEFAULT, new.cust_name, new.cust_address); INSERT
> INTO tbl_order VALUES (NEW.ord_pieces, NEW.ord_productname,
> NEW.ord_price, currval('"tbl_cusomer_cust_id_seq"')););
> 
> But this results in the same problem: It works fine if I insert just
> one new customer with one new order. But if I want to insert several
> new entries:

Insert the new customer only into the table if this customer doesn't
exist there. If the customer exist in the table, obtain the id for this
customer.


simplified:

- detect, if the customer exists
  yes: obtain the id as id
  no: insert and use currval() as id
- insert the order with the id


I would write a function for this.


Andreas
-- 
Andreas Kretschmer
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