John, You're making sense.
If you wanted to find all the systems used on project Test Bed Alpa, you'd do something like this: Select sys_name, s.id, project_name FROM systems s, new_req n,ie_sys_req i WHERE s.id = i.sys_id AND n.id = i.proj_name_id AND n.id = 344; Hope this helps, Andy mysql query > -----Original Message----- > From: John Coder [mailto:jcoder@;insightbb.com] > Sent: 07 November 2002 14:59 > To: Richard Forgo > Cc: [EMAIL PROTECTED] > Subject: RE: Newbie: Intersecting entities > > > 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 > > --------------------------------------------------------------------- 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
