thanks to all respondents! one more thing, i have 2 foreign keys in the bridge table, but not a primary key. is a primary key in the bridge necessary for this type of join to work? thanks again.
Begin forwarded message: > From: Roger Karnouk <[EMAIL PROTECTED]> > Date: Wed Jan 23, 2002 03:25:06 PM US/Pacific > To: mike vogel <[EMAIL PROTECTED]>, [EMAIL PROTECTED] > Subject: RE: three-way join > > > > create table magazine > (Mag_id int primary key, > Name char(30)); > > create table customer > (cust_id int primary key, > name char(30)); > > create table bridge > (cust_id int not null, > mag_id int not null, > primary key(mag_id,cust_id)); > > insert into customer values > (10,'John'),(24,'Luke'),(43,'Tony'),(25,'Matt'); > > insert into magazine values (13,'carMag'),(25,'cosmo'),(9,'farmingMag'); > > insert into bridge values (10,13),(10,9),(24,13),(42,9),(25,25); > > select c.name from magazine m inner join bridge b on (m.mag_id = > b.mag_id) > inner join customer c on (c.cust_id = b.cust_id) > where m.Name = 'carmag'; > > -----Original Message----- > From: mike vogel [mailto:[EMAIL PROTECTED]] > Sent: Wednesday, January 23, 2002 5:51 PM > To: [EMAIL PROTECTED] > Subject: three-way join > > > i understand that creating a M:N relationship in mysql involves 3 > tables, one of which being a bridge, but how do i join the first and > third tables by way of a bridge? > > example: a table of subscribers and a table of magazines with a bridge > in the middle. how do i select just the magazines fred is subscribed to? > thanks in advance and sorry if this is a confusing question. > > > --------------------------------------------------------------------- > 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
