MySQL supports using InnoDB tables. CREATE TABLE customers ( num INT PRIMARY KEY, Name VARCHAR(50) NOT NULL);
CREATE TABLE sales( Product VARCHAR(15) NOT NULL, Price DOUBLE NOT NULL, Cust INT NOT NULL, # PRIMARY KEY definition goes here, INDEX (Cust), FOREIGN KEY(Cust) REFERENCES customers(num) ON DELETE RESTRICT ON UPDATE CASCADE); Now if the "num" changes in customer, MySQL automatically updates "Cust" on SALES. Adolfo > -----Original Message----- > From: David T-G [mailto:[EMAIL PROTECTED]] > Sent: Tuesday, December 03, 2002 5:36 PM > To: mysql users > Subject: relational is relational is relational, but ... > +------------------------+ +------------------------+ > | SALES | | CUSTOMERS | > +---------+-------+------+ +------+-----------------+ > | product | price | cust | | num | name | > +---------+-------+------+ +------+-----------------+ > | TXLblue | 14.99 | 1136 | | 1136 | richard roe | > +---------+-------+------+ +------+-----------------+ > | CMMblck | 11.50 | 2408 | | 2408 | jane doe | > +---------+-------+------+ +------+-----------------+ > | SMMblue | 22.75 | 2408 | | 8421 | bob smith | > +---------+-------+------+ +------+-----------------+ > > where SALES.cust gets filled with the same value as > CUSTOMERS.num -- but should the customer number somehow > change we're now out of sync, whereas in a truly relational > database the fields in the SALES.cust column would > *be* the fields in the CUSTOMERS.num column rather than > simply having the same value. > > Am I lost, out of my tree, confused, or bang on? And how > (perhaps InnoDB > tables) does MySQL support this if I'm not any of the first three? > > > TIA & HAND > > mysql query, > :-D > - -- > David T-G * There is too much animal courage in > (play) [EMAIL PROTECTED] * society and not sufficient > moral courage. > (work) [EMAIL PROTECTED] -- Mary Baker Eddy, > "Science and Health" > http://www.justpickone.org/davidtg/ Shpx gur > Pbzzhavpngvbaf Qrprapl Npg! > > -----BEGIN PGP SIGNATURE----- > Version: GnuPG v1.0.7 (FreeBSD) > > iD8DBQE97SO3Gb7uCXufRwARAooDAKDI6dhugjyejLAEwC5Sjl6Pjqz/nACcDoj0 > vUcEuhNZHvTYh+KjGz05/9Q= > =hZrX > -----END PGP SIGNATURE----- > > --------------------------------------------------------------------- > 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
