public void showTable(){
    try{

        how.res = how.stat.executeQuery("select * from students order by name ASC limit 100");

        while(how.res.next()){
            String id = how.res.getString(1);
            String name = how.res.getString(2);
            String contact = how.res.getString(3);

            Object[] content = {id,name,contact};
            DefaultTableModel model = (DefaultTableModel)jTable1.getModel();
            model.addRow(content);

        }
    }catch (Exception e){

    }
}

private void jButton3ActionPerformed(java.awt.event.ActionEvent evt) {
    // TODO add your handling code here:
    try{
        numClick+=100;
        how.res = how.stat.executeQuery("select * from students offset"+numClick+"");

        while(how.res.next()){
            String id = how.res.getString(1);
            String name = how.res.getString(2);
            String contact = how.res.getString(3);

            Object[] content = {id,name,contact};
            DefaultTableModel model = (DefaultTableModel)jTable1.getModel();
            model.addRow(content);
        }
    }catch (Exception e){

    }
}

public class JoinConnection {

public Connection con;
public Statement stat;
public ResultSet res;

public JoinConnection(){

    systemConnection();
}

public void systemConnection(){
    try{
    Class.forName("com.mysql.jdbc.Driver");
    con =(com.mysql.jdbc.Connection) DriverManager.getConnection("jdbc:mysql://localhost:3306/library","root","");
            stat = (Statement) con.createStatement();
    }catch(ClassNotFoundException | SQLException e){System.out.println(e);}
}