hi i was using JDBC in a progra 1

[vkarthik]

hi

i was using JDBC in a program when i got this problem. i had 2 buttons 'next'and 'back' to browse thro' the records in a table. i got the records into a ResultSet object with an sql query. the 'next' button works fine, but the 'back' button gives an exception like this
"The resultset is TYPE_FORWARD_ONLY" something like that. this happens when the line
rs.previous() is encountered. (same thing happens for methods like rs.first()).
i tried to use a method setFetchDirection() of the resultset class but that failed too. how do i move back in the resultset? plz help.
i vote for any answer i find useful.

luv
Karthik.

 

[Guest_imported]

Hi there - if you check out the Java docs on the java.sql.ResultSet interface (which any JDBC 2 driver must implement) there's the following specification :

"New methods in the JDBC 2.0 API make it possible to produce ResultSet objects that are scrollable and/or updatable. The following code fragment, in which con is a valid Connection object, illustrates how to make a result set that is scrollable and insensitive to updates by others, and that is updatable. See ResultSet fields for other options.

Statement stmt = con.createStatement (
ResultSet.TYPE_SCROLL_INSENSITIVE,
ResultSet.CONCUR_UPDATABLE);

ResultSet rs = stmt.executeQuery("SELECT a, b FROM TABLE2"

// rs will be scrollable, will not show changes made by others, and will be updatable
"

There's a of bunch of static constants in the class that can be used in the Connection.createStatement(} method to define the nature of the ResultSet. Hope that helps. RjB.

 

[SharadR]

I don't know if this solution is the perfect answer....but once you browse through a record set I think you cannot go back to it....The best option would be to get all the records and save them in a vector or something and then browse the vector..... Thats what I had done....

Hope it helps

Sharad

 

[richardbergquist]

Yes, you can browse fowards and backwards thru a ResultSet w/ JDBC2 using ResultSet.TYPE_SCROLL_INSENSITIVE in the Connection.createStatement method.

Sharad's approach is fine if you want to make a local copy of the data for cursor query performance (if you have a slow JDBC connection over a WAN) but it has the following disadvantages
[1] Extra coding effort
[2] As you have cached a local copy of the data you cannot make use of ResultSet.TYPE_SCROLL_SENSITIVE in the Connection.createStatement method to make your result set sensitive to changes made by others (which can be very important for dynamic data in a multiuser DBMS).

RjB.

 

[vkarthik]

thanx all. will try all ur methods and see if it works. thanx again.

luv
Karthik.

 

[bonnScott]

Hey mate that's a stupid problem you've got there!
The only thing you have to do is to specify your resultset as TYPE_SCROLL_INSENSITIVE so that your cursor may fool around in any direction. I had the same problem when I first started Java blaming it to be some geeky stuff, but then I discovered the scroll insensitive thing.
Try that ok?

Take care mate!

 

[Rishu]

(May be u r looking for this vkarthik SIR)
/* FIRST PREVIOUS NEXT LAST
________________________ */

TRY USING THIS CODE

import java.awt.*;
import java.sql.*;
import java.awt.event.*;
import java.util.*;


public class JDBC1 extends Frame implements ActionListener
{
Label l1,l2,l3,l4;
Button b1,b2,b3,b4;
TextField t1,t2,t3;
String drive;
Connection c;
String du;
String sql;
int max=0,p1;
int i=1;
String arr1[][] = new String[100][4];


public JDBC1()
{
setLayout(null);
l1=new Label("QUERY FORM"
l2=new Label("Ecode"
l3=new Label("Name"
l4=new Label("Salary"
t1=new TextField(20);
t2=new TextField(20);
t3=new TextField(20);
b1=new Button("first"
b2=new Button("previous"
b3=new Button("next"
b4=new Button("last"
l1.setBounds(200,30,100,40);
l2.setBounds(20,80,150,20);
l3.setBounds(20,120,150,20);
l4.setBounds(20,160,150,20);
t1.setBounds(200,80,250,20);
t2.setBounds(200,120,250,20);
t3.setBounds(200,160,250,20);
b1.setBounds(150,470,100,40);
b2.setBounds(250,470,100,40);
b3.setBounds(350,470,100,40);
b4.setBounds(450,470,100,40);
this.add(l1);
this.add(l2);
this.add(t1);
this.add(l3);
this.add(t2);
this.add(l4);
this.add(t3);
this.add(b1);
this.add(b2);
this.add(b3);
this.add(b4);
b1.addActionListener(this);
b2.addActionListener(this);
b3.addActionListener(this);
b4.addActionListener(this);

try{
drive="sun.jdbc.odbc.JdbcOdbcDriver";
Driver dr=(Driver)Class.forName(drive).newInstance();
Properties p=new Properties();
/* fa1 is the name of the dsn created in control panel 32odbc by using database of access2000*/
du="jdbcdbc:fa1";
c=dr.connect(du,p);
Statement stmt=c.createStatement();
String s ="select * from Table2";
ResultSet result=stmt.executeQuery(s);
this.setSize(300,300);
this.show();
while(result.next())
{
arr1[1]=result.getString(1);
arr1[2]=result.getString(2);
arr1[3]=result.getString(3);
i++;
max=i-1;
}
}catch(SQLException e)
{
System.out.println("Error" + e);
} catch(Exception ee)
{
System.out.println("Error "+ ee);
}
for(int i=0;i<=max;i++)
{
for(int j=0;j<=3;j++)
{
System.out.println(arr1[j]);

}
}
}



public void actionPerformed(ActionEvent e)
{

// FIRST

if(e.getSource()==b1)
{

t1.setText(arr1[1][1]);
t2.setText(arr1[1][2]);
t3.setText(arr1[1][3]);
i=2;
}


//NEXT

if(e.getSource()==b3)
{
if(i<=max && i >=1)
{
t1.setText(arr1[1]);
t2.setText(arr1[2]);
t3.setText(arr1[3]);

p1=i-1;i++;
}
}

//PREVIOUS

if(e.getSource()==b2)
{
if(p1<=max && p1 >=1)
{
t1.setText(arr1[p1][1]);
t2.setText(arr1[p1][2]);
t3.setText(arr1[p1][3]);
p1--;
i=p1;
}
}

// LAST

if(e.getSource()==b4)
{

t1.setText(arr1[max][1]);
t2.setText(arr1[max][2]);
t3.setText(arr1[max][3]);
p1=max-1;

}

}


public static void main(String ar[])
{

JDBC1 J= new JDBC1();


}}

FROM

RISHU CHOPRA

 

[vkarthik]

thanx sharad, ur method works nicely. i've voted 4 ur tip. bonscott im yet to try ur idea. thanx rishu 4 takin the pain of writing so much code. thanx again.

luv
Karthik.
Pearls and Diamonds are not found on surfaces.