If the following integer field is NULL, will the following expression evaluate as 1) false or 2) indeterminant?

If ( FieldByName('ItemNo').AsInteger > 0 )

Bill


My money is on 1). Whilst the SQL standard has (IMHO) horrible things to say about null .AsInteger has to do something with it and I think that something is treat it as zero.

Roy Lambert

Bill,

<< If the following integer field is NULL, will the following expression
evaluate as 1) false or 2) indeterminant?

If ( FieldByName('ItemNo').AsInteger > 0 )  >>

False because Delphi doesn't know anything about NULL values.  To determine
if a field is NULL, use the TField.IsNull property instead.

--
Tim Young
Elevate Software
www.elevatesoft.com

Bill Edwards wrote:
> If the following integer field is NULL, will the following expression evaluate as 1) false or 2) indeterminant?
>
> If ( FieldByName('ItemNo').AsInteger > 0 )
>
All the TField.AsXXX will return a value. For a null field, the value is:

Boolean ==> False
String ==> ''
Numeric ==> 0 (This includes TDateFields which evaluate to Dec 31, 1899
or something like that)

So, this expression will evaluate to False if the field 'ItemNo' is null.

Sean