Re: Subquery in constraints...
From: Mikito Harakiri <mikharakiri_at_iahu.com>
Date: Mon, 11 Oct 2004 10:58:26 -0700
Message-ID: <73Aad.41$UF1.145_at_news.oracle.com>
Date: Mon, 11 Oct 2004 10:58:26 -0700
Message-ID: <73Aad.41$UF1.145_at_news.oracle.com>
AFAIK MS Server allows User Defined Methods (and, therefore, subqueries) in check constraint clause.
Unfortunately, the matter is much much more complicated than it appears at the first sight. Allowing UDFs and subqueries in the constraints has nontrivial implications as far as performance and locking are concerned. Suppose you implement foreign key constraint as a subquery in the check constraint clause. Would the DBMS be smart enough to leverage existing index on the parent_id column? Would it handle concurrency correctly?
"<Leander>" <leander_at_net.hr> wrote in message
news:ckdod1$o61$1_at_ls219.htnet.hr...
> Which RDBMS supports subquery in constraints?
>
>
Received on Mon Oct 11 2004 - 19:58:26 CEST