In the last episode (Sep 12), compo guy said: > What is the difference between the following sql queries written to > extract tuples with the field amount having non null value: > select loan_number from loan where amount <> null (It returns > an empty set) > select loan_number from loan where amount is not null(It > returns the expected result).
NULL is a special value. it can only be compared with "IS NULL" or "IS NOT NULL". "= NULL" and "<> NULL" always return false. http://www.mysql.com/doc/en/Working_with_NULL.html -- Dan Nelson [EMAIL PROTECTED] --------------------------------------------------------------------- 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
