MapInfo does not know a NULL - Value,
this is one of the great weaknesses of MapInfo/MapBasic, especially when working with databases, there is often the situation where NULL has a complete different meaning than a 0 in a numeric column for example.
If you access Database data with NULL Values, these values are shown in
MapInfo by a 0 for numeric values and by "" empty string for character Values,
maybe there may be improvements in versions 8.x, i still hope for that.
Regards
Hughes, Colleen / Don Mitchell wrote:
Hi Bill,
my curiousity is up now.
I am not familiar with nulls in MapBasic myself, but I noticed in MapInfo a null is a 0 (zero) if the field is numeric and a string field is an empty string (i.e. ""). At least this is how it is handled in the SQL.
In a string situation, is the empty string in quotations also evaluated as 0 (zero) programmatically by MapInfo?
Don Mitchell
-----Original Message----- From: Bill Thoen [mailto:[EMAIL PROTECTED] Sent: December 7, 2004 5:07 PM To: John Polasky Cc: [EMAIL PROTECTED] Subject: Re: MI-L MapBasic Null Value
On Tue, 7 Dec 2004, John Polasky wrote:
Using an If...Then statement, how do I tell MapInfo to identify that the
variable is empty? I can't use zero for the check obviously, but is
there a MapBasic code that identifies a null value?
No. A blank is the same as a zero to MapInfo.
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