On Wed, 2002-11-06 at 23:25, Richard Forgo wrote: > Sorry for being vague. I think the closest thing I can find to it is, > possibly, a three-way join. I'm trying to figure out how to write the > query. > > I've got the following tables: > > systems > ------------------------ > sys_name ID > ------------------------ > Abrams 202 > Patriot 544 > Stinger 229 > > ... and ... > > new_req > ------------------------ > proj_name ID > ------------------------ > Test Bed Alpha 344 > Tracked Wheels 989 > Battle Monitor 823 > Shoulder Harness 654 > Ammo Flask 454 > Spotter 773 > > There may be multiple new requirements for a single system. To > accommodate them, I created a new table -- an intersecting entity is > what I recall it being called -- to bridge the two. I can't keep the > multiple references to new_req in the systems table, nor can I keep them > in the new_req table. As best I can figure, I need to have a bridge > table ... e.g., > > ie_sys_req > ------------------------ > sys_id proj_name_id > ------------------------ > 202 344 > 202 989 > 202 823 > 544 654 > 544 454 > 544 773 > > If this seems peculiar, have patience with me I'm new at this. If it's > right, let me know so I can breath a sigh of relief. And if the > structure is right, could someone offer some guidance on how a query > that allows me to query new_req using the intersecting entity (or > three-way join, whatever it's called) would be written. > > Thanks, > > > Rik Forgo > JIST3 > Army Test, Training and Technology Integration Office (T3I) > Diverse Technologies Corp. > (c) 443.463.8571 > (h) 410.859.8474 > > > > -----Original Message----- > > From: John Ragan [mailto:jragan@;arkansas.net] > > Sent: Wednesday, November 06, 2002 6:55 PM > > To: [EMAIL PROTECTED]; Richard Forgo > > Subject: Re: Newbie: Intersecting entities > > > > > > if a succinct statement is possible, perhaps you > > could give us an idea of its nature? > > > > somebody may be familiar with the concept under a > > different name. > > > > > > > I'm trying to find some documentation on creating intersecting > entities > > > in MySQL, but haven't been able to track any info down on the MySQL > site > > > or on the web. At least we called them intersecting entities while > I > > > was in Oracle training (which was some time ago). I think I > remember > > > how to set them up, but I'd love to have something to refer to > quickly > > > before I start. Can anyone point me in the right direction? > > >
There is an example and full blown script in a book by Michael Koffler called MYSQL. His Url is www,Kofler.cc If I remember it correctly he had a "intersecting entity" involving Authors and Publishers in his mylibrary example. John Coder --------------------------------------------------------------------- Before posting, please check: http://www.mysql.com/manual.php (the manual) http://lists.mysql.com/ (the list archive) To request this thread, e-mail <[EMAIL PROTECTED]> To unsubscribe, e-mail <[EMAIL PROTECTED]> Trouble unsubscribing? Try: http://lists.mysql.com/php/unsubscribe.php
