Re: AW: AW: [HACKERS] Re: [SQL] behavior of ' = NULL' vs. MySQL vs. S tand ards
Zeugswetter Andreas SB [EMAIL PROTECTED] writes: Thus it could be, that NULL in where column = NULL is not defined to have a special meaning according to SQL92. The way I interpret Celko's interpretation of SQL92, that specific construct has a meaning; it evaluates to UNKNOWN, thus not to TRUE, and the WHERE clause becomes useless, as does any other combination of a theta operator and the explicit constant 'NULL'. This is almost, but not quite, an argument for allowing = NULL for IS NULL. ;-) Does anyone out there have the actual text of the standard? -tih -- The basic difference is this: hackers build things, crackers break them. ---(end of broadcast)--- TIP 5: Have you checked our extensive FAQ? http://www.postgresql.org/users-lounge/docs/faq.html
AW: AW: AW: [HACKERS] Re: [SQL] behavior of ' = NULL' vs. MySQL vs. S tand ards
Thus it could be, that NULL in where column = NULL is not defined to have a special meaning according to SQL92. The way I interpret Celko's interpretation of SQL92, that specific construct has a meaning; it evaluates to UNKNOWN, thus not to TRUE, Imho the text refers to a content of a particular column of one particular row. where table1.col1 = table2.col1 the content of table2.col1 is null -- comparison evaluates to UNKNOWN. It does not state whether NULL is a valid constant expression. Andreas ---(end of broadcast)--- TIP 2: you can get off all lists at once with the unregister command (send unregister YourEmailAddressHere to [EMAIL PROTECTED])
Re: AW: AW: [HACKERS] Re: [SQL] behavior of ' = NULL' vs. MySQL vs. S tand ards
On Thu, Jun 07, 2001 at 02:46:50PM +0200, Tom Ivar Helbekkmo wrote: Zeugswetter Andreas SB [EMAIL PROTECTED] writes: Thus it could be, that NULL in where column = NULL is not defined to have a special meaning according to SQL92. The way I interpret Celko's interpretation of SQL92, that specific construct has a meaning; it evaluates to UNKNOWN, thus not to TRUE, and the WHERE clause becomes useless, as does any other combination of a theta operator and the explicit constant 'NULL'. This is almost, but not quite, an argument for allowing = NULL for IS NULL. ;-) Does anyone out there have the actual text of the standard? -tih I dont know the standard for that, but to add an experience in another server (Interbase), '= null' has no meaning in Interbase, ie, doesnt works as 'IS NULL'. Sergio Bruder -- ( )) (tm)http://sergio.bruder.net ||-. http://pontobr.org |__|-' [EMAIL PROTECTED], [EMAIL PROTECTED] -- pub 1024D/0C7D9F49 2000-05-26 Sergio Devojno Bruder [EMAIL PROTECTED] Key fingerprint = 983F DBDF FB53 FE55 87DF 71CA 6B01 5E44 0C7D 9F49 sub 1024g/138DF93D 2000-05-26 ---(end of broadcast)--- TIP 3: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly
