On Sun, Dec 16, 2001 at 09:33:06PM +0200, Heikki Tuuri wrote: > I will change InnoDB so that it allows several NULL values in secondary > indexes even if that index would have been declared UNIQUE. Oracle has a > similar convention. > > In the case of foreign keys, I advise against using NULL values, because in > SQL NULL really means 'an unknown value'.
Would it not make sense to not 'match' foreign NULL values at all? That is, to ignore them entirely when used as foreign keys, as though the row was not there? If, for example, CustID in one table must match Cust.ID in another and CustID is NULL (and the column allows this), would it be ignored or require a 'matching' NULL as a Cust.ID value? -- Michael T. Babcock CTO, FibreSpeed Ltd. (Hosting, Security, Consultation, Database, etc) http://www.fibrespeed.net/~mbabcock/ --------------------------------------------------------------------- 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
