Re: howto figure out if ResultSet is empty

[Mihael Knezevic <m.knezevic@xxxxxxxx>]

allready thought of something like that. thanx.

On 2002.08.09 12:55 Richard Dettinger wrote:
>
> re: I think that if no rows are returned, rather
> than an empty ResultSet you get a null one;
>
> No, you should get a ResultSet which is empty.  Calling next() the first
> time will return false.  So the
> code example below will always work.  If you needed to know to do
> something
> different when it was
> empty, you could probably either keep a int count inside your while loop
> which you checked after
> the loop ended (if the int was still 0, it was null).
>
> Or perhaps something like this:
>
> int i;
> for (i = 0; rs.next(); i++) {
>       // process row.
> }
>
> if (i == 0) {
>       // handle empty case.
> }
>
> There are other things that should work as well with scrollable
> resultSets.
> (such as using
> first() or isBeforeLast()), but my experience is that different drivers
> would be more spotty
> and less consistant in this area and something like the above solution is
> a
> better idea.
>
> Richard D. Dettinger
> iSeries Java Data Access Team
>
> Democracy's enemies have always underestimated the courage of the
> American
> people.
> It was true at Concord Bridge.  It was true at Pearl Harbor.  And it was
> true today.
>
>          Rochester Post-Bulletin
>          Tuesday September 11, 2001
>
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> |         |           Martin"          |
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>   |       Subject:  RE: howto figure out if ResultSet is empty
>                                                        |
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>>------------------------------------------------------------------------------------------------------------------------------|
>
>
>
> Mihael Knezevic wrote:
>
> > howto figure out if ResultSet is empty ?
> >
> > my code looks like this:
> >
> > Statement statement;
> > ResultSet rs;
> >
> > String stm = "Select xxx from xxx.xxx where xxx";
> >
> > rs = statement.executeQuery(stm);
> >
> > while(rs.next())
> > {
> >            do.something();
> > }
>
> I'm not entirely sure, but I think that if no rows are returned, rather
> than an empty ResultSet you get a null one; so just test it for null
> first.  As well as that, if there is no row available (presumably, even
> if there are no rows to begin with) next() should return false.
>
> Cheers,
>
> Martin.
>
> --
> Martin McCallion
> Senior Technical Consultant
> Work:  martin.mccallion@misys.com
> Home: martin.mccallion@ukonline.co.uk
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