Question of the Day for 01 Mar 2007

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Question of the Day for 01 Mar 2007

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Deepak Sharma-2311

Posted Wednesday, July 29, 2009 3:17 AM

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This question is quite wrong. The SET key word can not be used by = (EqualTo operator). The correct syntax is:
SET ANSI_NULLS OFF
this is wrong:
SET ANSI_NULLS= OFF

Deepak Kumar Sharma

Post #761351

peratchiselvi.m

Posted Tuesday, March 23, 2010 3:54 AM

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In the answer for this question, "The expression "MyID = NULL" evaluates to Unknown rather than any true or false condition."
then y it is false... instead of unknown. can anyone pls answer this...

Post #887935

Jasmine D. Adamson

Posted Tuesday, March 23, 2010 9:28 AM

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peratchiselvi.m (3/23/2010)

In the answer for this question, "The expression "MyID = NULL" evaluates to Unknown rather than any true or false condition."
then y it is false... instead of unknown. can anyone pls answer this...

It isn't "false" it is "null" - but it will fail in a where clause or case statement because it's "not true"

Post #888232

peratchiselvi.m

Posted Wednesday, March 24, 2010 5:38 AM

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s. ssc went wrong there then.... thank u...

Post #888831

Jasmine D. Adamson

Posted Wednesday, March 24, 2010 10:07 AM

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peratchiselvi.m (3/24/2010)

s. ssc went wrong there then.... thank u...

No not really, it's a kind of a trick question... when you use the = operator and compare to null, the result is always unknown rather than true or false. The proper expression is "IS NULL" which will evaluate to true or false rather than unknown. That's what the question was about.

Post #889095

peratchiselvi.m

Posted Wednesday, March 24, 2010 9:59 PM

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ok. ok. got it....thanks.

Post #889519

L' Eomot Inversé

Posted Tuesday, April 20, 2010 3:42 PM

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I read this question, decided it was a bit weird because where clauses don't evaluate to anything and concluded that it must be asking what truth-value/values the expression in the where clause evaluates to and ansered accordingly (UNKNOWN). The answer given as correct is FALSE. The explanation simply says that the contained expression always evaluates UNKNOWN, and doen't make any suggestion of how FALSE comes from here. I guess the author has invented a new terminology: in this new terminology a filter evaluates to something instead of including or excluding a row, and "evaluates to false" means "excludes the current row". That's not very useful, as the existing terminology makes perfect sense.

Tom
Que conclure à la fin de tous mes longs propos? C'est que les préjugés sont la raison des sots. (Voltaire, 1756)

Post #907310

kapil_kk

Posted Tuesday, November 27, 2012 5:21 AM

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easy one for NULL Smile

Post #1389116

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