daniel kessler wrote: >> On 7/5/05, Daniel Kessler <[EMAIL PROTECTED]> wrote: >>> >>> AND cs_price <> <cfqueryparam cfsqltype="cf_sql_varchar" >>> value=""> >> >> AND cs_price IS NOT NULL > > this worked great! thanks! > > but why? IOW, why does this work, but these do not: > AND cs_price <> NULL > AND cs_price != NULL
Because NULL is special. NULL means unknown. The outcome of every operation on unknown is unknown. The only exception is the special 'IS (NOT) NULL' case which will return TRUE or FALSE. A predicate like 'cs_price <> 3' will filter the returned data and will only pass rows where the expression returns TRUE. Since 'cs_price <> 3' will always return NULL when cs_price is NULL, records with a NULL are excluded from the result. Jochem ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~| Logware (www.logware.us): a new and convenient web-based time tracking application. Start tracking and documenting hours spent on a project or with a client with Logware today. Try it for free with a 15 day trial account. http://www.houseoffusion.com/banners/view.cfm?bannerid=67 Message: http://www.houseoffusion.com/lists.cfm/link=i:4:211245 Archives: http://www.houseoffusion.com/cf_lists/threads.cfm/4 Subscription: http://www.houseoffusion.com/lists.cfm/link=s:4 Unsubscribe: http://www.houseoffusion.com/cf_lists/unsubscribe.cfm?user=11502.10531.4 Donations & Support: http://www.houseoffusion.com/tiny.cfm/54
