Re: Number of rows in a ResultSet ?

Quoting Michael Stephenson <mstephenson(at)tirin(dot)openworld(dot)co(dot)uk>:

> > I need to know how many rows exist in a ResultSet. I've tried to use
> > getFetchSize() method of ResultSet interface, but a message was
> > displayed "this method is not yet implemented".
> >
> > Anyone can help me ?
>
> You could use:
> ResultSet.last();
> int numberOfRows = ResultSet.getRow();
>
> Now, my understanding of this area is a but sketchy, but I think that
> most implementations of ResultSet do not get all of the results in one
> go
> (like the PostgreSQL JDBC driver does), so getFetchSize() is not a safe
> way of determining the number of results returned.

Until about 30 minutes ago getFetchSize() threw an SQLException as it wasn't
implemented ;-)

For normal ResultSet's in 7.1 getFetchSize() will return the number of rows,
but I'd advise you use Michael's suggestion as it's probably the safest bet for
TYPE_SCROLL_INSENSITIVE & TYPE_SCROLL_SENSITIVE ResultSets (remember
technically TYPE_FORWARD_ONLY ResultSet's should not allow you to go back after
the .last() call).

Peter
>
> Or, you could do another query with count() in your sql..
>
> Or (and I wouldn't do this without carefully looking at the jdbc spec),
> you could just alter the getFetchSize() method
> org.postgresql.jdbc2.ResultSet driver to look like:
>
> public int getFetchSize() throws SQLException
> {
> return rows.size();
> }
>
> The choice is yours..
>
> Michael Stephenson mstephenson(at)openworld(dot)co(dot)uk
> Developer - Web Applications - Open World
> Tel: +44 1225 444 950 Fax: +44 1225 336 738
>
>

--
Peter Mount peter(at)retep(dot)org(dot)uk
PostgreSQL JDBC Driver: http://www.retep.org.uk/postgres/
RetepPDF PDF library for Java: http://www.retep.org.uk/pdf/