From JTESTA@longaberger.com Mon, 27 Aug 2001 10:49:11 -0700 From: "JOE TESTA" Date: Mon, 27 Aug 2001 10:49:11 -0700 Subject: Re: PK/Fk question Message-ID: MIME-Version: 1.0 Content-Type: text/plain oh i definitely didnt include all of the problems associated with distributed enforcement of FK.  I was denoting the obvious :)   joe >>> jonathan@jlcomp.demon.co.uk 08/27/01 02:22PM >>>There is also the drawback that thetrigger has to do a 'select for update',with all associated contention problems,otherwise the effect of read-consistencywould allow a trigger to determine that aparent existed when in fact it had beendeleted by an uncommitted transaction.Jonathan LewisHost to The Co-Operative Oracle Users' FAQhttp://www.jlcomp.demon.co.uk/faq/ind_faq.htmlAuthor of:Practical Oracle 8i: Building Efficient DatabasesSee http://www.jlcomp.demon.co.uk/book_rev.htmlFor latest news of public appearancesSee http://www.jlcomp.demon.co.ukScreen saver or Life saver: http://www.ud.comUse spare CPU to assist in cancer research.-----Original Message-----To: Multiple recipients of list ORACLE-L Date: 27 August 2001 18:15You can only FK to field(s) that are unique or primary keyconstraints.if col1 is unique, you can put a unique constraint on it and then FKto it from the child.your only other choice is to do FK checkign via triggers(i did it fordistributed databases, where parents were on one db and children wereon other, efficient NO but it was a requirement).joe-- Please see the official ORACLE-L FAQ: http://www.orafaq.com-- Author: Jonathan Lewis  INET: jonathan@jlcomp.demon.co.ukFat City Network Services    -- (858) 538-5051  FAX: (858) 538-5051San Diego, California        -- Public Internet access / Mailing Lists--------------------------------------------------------------------To REMOVE yourself from this mailing list, send an E-Mail messageto: ListGuru@fatcity.com (note EXACT spelling of 'ListGuru') and inthe message BODY, include a line containing: UNSUB ORACLE-L(or the name of mailing list you want to be removed from).  You mayalso send the HELP command for other information (like subscribing).