So what's null then if it's not nothing?
From: <michael_at_preece.net>
Date: 16 Nov 2005 22:03:14 -0800
Message-ID: <1132207394.336133.241390_at_g44g2000cwa.googlegroups.com>
I've been accustomed to thinking of things either having a value or not. If something has no value then, to me, its value is null. Its value is an empty string (whatever "it" is). Different to having a value of zero. Different to anything with a value. Now, as I read up on SQL, I find that null is supposed to mean "unknown". I can't easily accept that. Does SQL's definition of null (unknown) include the null I'm familiar with (no value)? That doesn't make sense. If we know something has no value then its not an unknown value is it? I can't imagine having to write code where the "if a=b then result=true else result=false" construct won't work - according to what I'm reading, if either a or b is null then I should be setting result to unknown instead. Just can't get my head 'round that. Shouldn't things be a lot simpler? If something has an unknown value then at least we know whether it's null (as in an empty string) or not. To me, "unknown" can be compared with an empty string to see if it's null or not. Sorry - head is spinning.
Date: 16 Nov 2005 22:03:14 -0800
Message-ID: <1132207394.336133.241390_at_g44g2000cwa.googlegroups.com>
I've been accustomed to thinking of things either having a value or not. If something has no value then, to me, its value is null. Its value is an empty string (whatever "it" is). Different to having a value of zero. Different to anything with a value. Now, as I read up on SQL, I find that null is supposed to mean "unknown". I can't easily accept that. Does SQL's definition of null (unknown) include the null I'm familiar with (no value)? That doesn't make sense. If we know something has no value then its not an unknown value is it? I can't imagine having to write code where the "if a=b then result=true else result=false" construct won't work - according to what I'm reading, if either a or b is null then I should be setting result to unknown instead. Just can't get my head 'round that. Shouldn't things be a lot simpler? If something has an unknown value then at least we know whether it's null (as in an empty string) or not. To me, "unknown" can be compared with an empty string to see if it's null or not. Sorry - head is spinning.
Mike. Received on Thu Nov 17 2005 - 07:03:14 CET