Message-ID: <019801c2c31c$c8d63fa0$3200000a@K2>
From: "Luke Pascoe" <luke.p@kmg.co.nz>
To: <pgsql-sql@postgresql.org>
Subject: checking data integrity in a recursive table
Date: Fri, 24 Jan 2003 09:19:51 +1300
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Hi, I have a table that references itself to create a tree-like structure,
eg:
    CREATE TABLE tree (
        id     SERIAL NOT NULL,
        name   VARCHAR(255) NOT NULL,
        parent INT NULL,
        customer IN NOT NULL,
        CONSTRAINT parent_key...
        CONSTRAINT customer_fk FOREIGN KEY (customer) REFERENCES customer
        );
    ALTER TABLE tree ADD CONSTRAINT FOREIGN KEY (parent) REFERENCES tree;

As you can see tree also references the customer table.

What I need is a CHECK that will ensuer that any given "tree" row has the
same customer as its parent.
Remember that "parent" can also be NULL.

Or would this be better done as a trigger?

TIA!

========================================
Luke Pascoe
KMG (NZ) Limited. http://www.kmg.co.nz
Mobile: (021) 303019
Email: luke.p@kmg.co.nz
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