Javier,
You are cracking me up. Thanks.
William Louth
> -----Original Message-----
> From: Javier Borrajo [SMTP:[EMAIL PROTECTED]]
> Sent: Thursday, April 27, 2000 5:49 PM
> To: [EMAIL PROTECTED]
> Subject: Re: Cached Rowsets-do we need to use them
>
> I agree with Richard's strategy *but* I think it lacks an important
> feature:
> paging.
>
> You may want to check the thread "Paging large database result sets"
>
> Executive summary:
> 1. provide a method to get the count of records that fit the query
> 2. provide a method to get a pge of records
>
> So instead of:
>
> public class PayRollBean implements javax.ejb.SessionBean [
> public EJBResultSet getEmployeeSalaries( ){
> DataSource dataSource =
> (DataSource)cntx.lookup("java:comp/env/jdbc/db");
> Connection con = dataSource.getConnection( );
> Statement stmt = con.createStatement( );
> ResultSet set = stmt.executeQuery("select LNAME, FNAME, SALARY
> from
> EMPLOYEE");
>
> CustomResultSet customSet = new CustomResultSet(set);
> return (EJBResultSet)customSet;
> }
> ...
> }
>
> use:
>
> public class PayRollBean implements javax.ejb.SessionBean [
>
> public int getEmployeeSalariesCount(){
> DataSource dataSource =
> (DataSource)cntx.lookup("java:comp/env/jdbc/db");
> Connection con = dataSource.getConnection( );
> Statement stmt = con.createStatement( );
> ResultSet set = stmt.executeQuery("select COUNT(*) from
> EMPLOYEE");
> return set.getInt(1);
> }
>
> public Vector getEmployeeSalaries(int pini, int ptot){
> DataSource dataSource =
> (DataSource)cntx.lookup("java:comp/env/jdbc/db");
> Connection con = dataSource.getConnection( );
> Statement stmt = con.createStatement( );
> ResultSet set = stmt.executeQuery("select LNAME, FNAME, SALARY
> from
> EMPLOYEE");
>
> // get a page using JDBC 1.22
> /*int nrec = 0;
> int tot = pini+ptot;
> Vector result = new Vector();
> while( set.next() ) {
> if ( nrec++ < pini ) continue; // wasted effort JDBC 1.22
> if ( (ptot>0)&&(nrec>tot) ) break;// no more records, thank you
> result.addElement( makeAnObjectOutOfCurrentRecord() );
> }*/
>
> // get a page using JDBC 2.0
> absolute(pini);
> int nrec = 0;
> Vector result = new Vector();
> while( set.next() ) {
> //if <file://if> ( nrec++ < pini ) continue; // NO wasted effort
> using JDBC 2.0
> if ( (ptot>0)&&(++nrec>tot) ) break;// no more records, thank you
> result.addElement( makeAnObjectOutOfCurrentRecord() );
> }
> return result;
> }
> ...
> }
>
>
> The client first asks how many records fit the query, then asks for pages
> depending on the user actions.
>
> This way we are not collapsing the client memory with thousands of records
> it does not really need.
>
> Regards
>
> Javier
>
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