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Using NULL in Advanced Search
mgpw4me@yahoo.com:
I may have to update my movie rating system. Sex, Violence, Language = 3 star movie....
AimHere:
--- Quote from: rick.ca on March 06, 2010, 09:42:30 pm ---
--- Quote from: AimHere on March 06, 2010, 08:26:15 pm ---This is the only behavior that would really make sense to me, and I suspect, the majority of users.
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You've got to be kidding! The majority of users aren't even aware of the issue or haven't found a reason to care. Most of the rest are confused because the technical operation of the NULL operator does not yield a result that is intuitive in the circumstances. It's the lack of consideration of what is sensible to the average non-technical user that is the source of the problem in the first place.
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I suppose so. I'm only saying "if it were up to me"... ;D
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--- Quote ---And the conditions "IS NULL" and "= 0" should NOT be equivalent. A value of zero is still a value, not a "null". Then "null/not null" would have NO relation to "zero" (or any other value) other than the obvious (i.e. if the field contains "zero", then it is NOT "null").
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This is technically correct, but doesn't have any bearing on the question at hand, until it's decided it should. I contend that it should not. As I've pointed out a number of times in a number of different ways, there's no reason why NULL and 0 should not be equivalent—if that is simpler and appropriate for the situation at hand. I'm not suggesting there's no circumstance in which different meanings would be appropriate—but they do seem difficult to find. For most users in most situations, they both mean the same thing, and any attempt to make a distinction therefore only causes unnecessary confusion.
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I see your point.
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--- Quote ---And the various "Rating" fields should make a distinction between "blank/null/unrated" and "zero", instead of treating them as equivalent!
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And this is the perfect illustration of my general point. There's absolutely no justification for the assertion there "should" be "zero" rating. As a rating scale, there's nothing wrong with it starting at 1. It is, in fact, far more sensible than what you suggest. Using stars alone, there's no practical way to distinguish between NULL and 0. And there's no reason to rate something 0 when you can just as easily decide 1 has the exact same meaning. It's also obvious most users will find it perfectly intuitive the way it is. With a 0 rating allowed, we'd be forever explaining the distinction between "0" and "unrated."
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Also true enough.
I'd settle for having "IS NULL" versus "IS NOT NULL" testing return consistent, intuitive results regardless of which field is being tested.
Aimhere
CAD:
--- Quote ---There's absolutely no justification for the assertion there "should" be "zero" rating. As a rating scale, there's nothing wrong with it starting at 1. It is, in fact, far more sensible than what you suggest. Using stars alone, there's no practical way to distinguish between NULL and 0. And there's no reason to rate something 0 when you can just as easily decide 1 has the exact same meaning. It's also obvious most users will find it perfectly intuitive the way it is. With a 0 rating allowed, we'd be forever explaining the distinction between "0" and "unrated."
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--- Code: ---Enter Devil Advocate Mode
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There is nothing wrong with having a rating scale starting at 0.
If a movie is a real stinker 0 is perfectly valid.
null and 0 are different.
0 is a value - by definition - the value between + and - numbers
null is not populated. ie the field in question is empty. ( an invisible character eg "space" is a value and does not meet "null" criteria ).
I can see merit in having a rating system starting at 0 and null.
eg.
a movie is a stinker would be 0.
I haven't given this movie a rating yet would be null
Both should be independently searchable.
--- Quote ---Using stars alone, there's no practical way to distinguish between NULL and 0.
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perhaps if the movie is unrated " there is no spoon " err - there are no stars (displayed).
--- Code: ---Exit Devil Advocate Mode
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rick.ca:
True to the Devil's Advocate tradition, you've presented a classic one-star argument that helps us all accept the foregone conclusion the rating scale is fine the way it is. 8)
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