The sentence: "According to their example, if you wanted to select more rows, it would look something like below:"
should read: "According to their example, if you wanted to select more COLUMNS, it would look something like below:" Ali --- Paulo Alvim <[EMAIL PROTECTED]> wrote: > Thank you, Ali! I'll take a look... > > -----Mensagem original----- > De: Suavi Ali Demir [mailto:[EMAIL PROTECTED] > Enviada em: sábado, 30 de julho de 2005 21:57 > Para: Derby Discussion > Assunto: Re: how to fetch specific number of rows? > > > Hi Paulo, > > This asp page discusses different ways of doing what > you want: > http://www.aspfaq.com/show.asp?id=2120 > > One of the easy SQL ways discussed there is: > > To fetch 5 rows at a time and get the 3rd page you > would use this sql: > > SELECT > a.empno > FROM > employee a > INNER JOIN employee b > ON > a.empno>=b.empno > GROUP BY > a.empno > HAVING > COUNT(*) BETWEEN 11 AND 15 > ORDER BY > a.empno > > According to their example, if you wanted to select > more rows, it would look something like below: > > > SELECT > a.firstname, a.midinit, a.lastname > FROM > employee a > INNER JOIN employee b > ON > a.firstname||a.midinit||a.lastname >= > b.firstname||b.midinit||b.lastname > GROUP BY > a.firstname, a.midinit, a.lastname > HAVING > COUNT(*) BETWEEN 11 AND 15 > ORDER BY > a.firstname, a.midinit, a.lastname > > Being forced to ORDER BY all columns you select > should > be OK since your pages need to come in some order. > However I have no idea how this sql would perform, > especially for many columns. Also, while doing > a.firstnme||a.midinit||a.lastname you may get > unintended result but going the simple > a.firstname>=b.firstname way does not work. > > > I think in JSF, the way Sun's table impl implements > this is that they get a ResultSet and loop though > the > rs.next() until they reach the page they want. That > may perform better in some cases (especially in > embedded mode Derby, since you won't send extra rows > over the wire). > > Regards, > Ali > > > --- Paulo Alvim <[EMAIL PROTECTED]> wrote: > > Hi! > > > > I'm trying to use Derby to fetch "blocks" of X > > records each time in that > > kind of "web navigator" ("20 records from 100 to > > 120"). Ex: I use "rownum" > > in Oracle... > > > > How can I do it using Apache Derby? (Of course we > > can't keep cursors opened, > > etc.) > > > > Thanks in advance! > > > > Paulo Alvim > > Powerlogic > > Brazil > > > > > > > > > > >
