Re: Null vs. nothing
- From: "Arno R" <arraNOcomSPAM@xxxxxxxxxx>
- Date: Thu, 31 Aug 2006 00:29:28 +0200
"Rich P" <rpng123@xxxxxxx> schreef in bericht news:44f60098$0$34073$815e3792@xxxxxxxxxxxxxxxxx
Null means "Unknown"
Nothing is equivalent to "Empty".
Interesting...
Sorry Rich but I disagree on this.
Null does *not* mean unknown in my understanding of this issue.
(But I could be wrong...)
Null does not mean "Empty". It is possible to have characters that are
not displayed in a field - non-displaying ascii chars.
In that case the field is not Null (IsNull = False) Or ???
A field that is Null is an empty field in my understanding.
(But I could be wrong...)
These could
qualify as Null values because they are unknown. For the most part,
null fields usually are empty, but null still means that the value in
the field is unknown.
Rich
Think of something like a faxnumber.
When the field is Null we don't know whether there is a fax or not.
The field is not filled in. It is just empty.
Null is similar to empty (There is nothing in the field, the field is empty or deleted.)
When the field is empty we don't know whether there is a fax or not.
When we fill in a ZLS ("") there IS a fax BUT we know, that we don't know the number...
At least that's how I have understood the issue of ZLS.
(But I could be wrong...)
Anyhow: I hate ZLS strings and hardly ever (if I can: never) use them.
I hate ZLS because for the user the field is empty, and there is no visible difference with a Null-value (for the user)
I prefer to use something like <unknown> for the occasion where we know the fax IS there but the number is unknown.
Arno R
.
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