Problem while viewing a ResultSet in JDBC

[vinoth vino]

Now i m learning ResultSet types in java. Here, I've coded for viewing records in different ways.... At first i displayed the whole records which is in emp4 table and then i started to view these records in different manner(last,first,next) This is exactly what i am looking for but it won't display the all records which are presented in the emp4 table. See the First Program it doesn't work but if i documented the line 41(see this in Second Program) it just working awesome.... What's the problem ? is there any wrong with my code ???

CODE SAMPLE 1

package demojdbc;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.Statement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class MysqlCon{
	
	private static final String DB_DRIVER = "com.mysql.jdbc.Driver";
	private static final String DB_CONNECTION = "jdbc:mysql://localhost:3306/vinoth";
	private static final String DB_USER = "root";
	private static final String DB_PASSWORD = "vino";
	
	    public static void main(String args[])throws SQLException{
	    	
	    	//Creating statement and connection 
	    	Connection dbConnection = null;
	    	Statement stmt = null;
	    	
	    	try{
	    		
	    		//Creating class driver
	    		Class.forName(DB_DRIVER);
	    		
	    		//Creating Database Connection
	    		dbConnection = DriverManager.getConnection(DB_CONNECTION,DB_USER,DB_PASSWORD);
	    		
	    		//Creating statement
	    		stmt = dbConnection.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,ResultSet.CONCUR_READ_ONLY);
	    		
	    		//Creating query
	    		String sql = "SELECT id,gmail,yahoo from emp4";
	    		
	    		//Creating ResultSet
	    		ResultSet rs = stmt.executeQuery(sql);
	    		
	    		//Displaying database
	    		System.out.println("Displaying records before doing some operations");
	    		System.out.println(rs.getInt(1)+" "+rs.getString(2)+" "+rs.getString(3));
	    		
	    		System.out.println("Displaying records for last row");
	    		rs.last();
	    		
	    		int id = rs.getInt("id");
	    		String gmail = rs.getString("gmail");
	    		String yahoo = rs.getString("yahoo");
	    		
	    		//Displaying records in last row
	    		System.out.println("ID : "+id);
	    		System.out.println("GMAIL : "+gmail);
	    		System.out.println("YAHOO : "+yahoo);
	    		
	    		System.out.println();
	    		rs.first();
	    		System.out.println("Displaying records for first row");
	    		
	    		id = rs.getInt("id");
	    		gmail = rs.getString("gmail");
	    		yahoo = rs.getString("yahoo");
	    		
	    		//Displaying records in last row
	    		System.out.println("ID : "+id);
	    		System.out.println("GMAIL : "+gmail);
	    		System.out.println("YAHOO : "+yahoo);
	    		
	    		System.out.println();
	    		rs.next();
	    		System.out.println("Displaying records for next row");
	    		
	    		id = rs.getInt("id");
	    		gmail = rs.getString("gmail");
	    		yahoo = rs.getString("yahoo");
	    		
	    		//Displaying records in last row
	    		System.out.println("ID : "+id);
	    		System.out.println("GMAIL : "+gmail);
	    		System.out.println("YAHOO : "+yahoo);
	    		
	    	}catch(SQLException e){
	    		
	    		e.printStackTrace();
	    		
	    	}catch(ClassNotFoundException e){
	    		
	    	     System.out.println("Plese check the driver class path "+e.getMessage());
	    		
	    	}finally{
	    		
	    		if(stmt != null){
	    			
	    			stmt.close();
	    			
	    		}
	    		if(dbConnection != null){
	    			
	    			dbConnection.close();
	    			
	    		}
	    	}
	    }
}

Here, the code will works fine.....

CODE SAMPLE 2

package demojdbc;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.Statement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class MysqlCon{
	
	private static final String DB_DRIVER = "com.mysql.jdbc.Driver";
	private static final String DB_CONNECTION = "jdbc:mysql://localhost:3306/vinoth";
	private static final String DB_USER = "root";
	private static final String DB_PASSWORD = "vino";
	
	    public static void main(String args[])throws SQLException{
	    	
	    	//Creating statement and connection 
	    	Connection dbConnection = null;
	    	Statement stmt = null;
	    	
	    	try{
	    		
	    		//Creating class driver
	    		Class.forName(DB_DRIVER);
	    		
	    		//Creating Database Connection
	    		dbConnection = DriverManager.getConnection(DB_CONNECTION,DB_USER,DB_PASSWORD);
	    		
	    		//Creating statement
	    		stmt = dbConnection.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,ResultSet.CONCUR_READ_ONLY);
	    		
	    		//Creating query
	    		String sql = "SELECT id,gmail,yahoo from emp4";
	    		
	    		//Creating ResultSet
	    		ResultSet rs = stmt.executeQuery(sql);
	    		
	    		//Displaying database
	    		System.out.println("Displaying records before doing some operations");
	    		System.out.println(rs.getInt(1)+" "+rs.getString(2)+" "+rs.getString(3));
	    		
	    		System.out.println("Displaying records for last row");
	    		rs.last();
	    		
	    		int id = rs.getInt("id");
	    		String gmail = rs.getString("gmail");
	    		String yahoo = rs.getString("yahoo");
	    		
	    		//Displaying records in last row
	    		System.out.println("ID : "+id);
	    		System.out.println("GMAIL : "+gmail);
	    		System.out.println("YAHOO : "+yahoo);
	    		
	    		System.out.println();
	    		rs.first();
	    		System.out.println("Displaying records for first row");
	    		
	    		id = rs.getInt("id");
	    		gmail = rs.getString("gmail");
	    		yahoo = rs.getString("yahoo");
	    		
	    		//Displaying records in last row
	    		System.out.println("ID : "+id);
	    		System.out.println("GMAIL : "+gmail);
	    		System.out.println("YAHOO : "+yahoo);
	    		
	    		System.out.println();
	    		rs.next();
	    		System.out.println("Displaying records for next row");
	    		
	    		id = rs.getInt("id");
	    		gmail = rs.getString("gmail");
	    		yahoo = rs.getString("yahoo");
	    		
	    		//Displaying records in last row
	    		System.out.println("ID : "+id);
	    		System.out.println("GMAIL : "+gmail);
	    		System.out.println("YAHOO : "+yahoo);
	    		
	    	}catch(SQLException e){
	    		
	    		e.printStackTrace();
	    		
	    	}catch(ClassNotFoundException e){
	    		
	    	     System.out.println("Plese check the driver class path "+e.getMessage());
	    		
	    	}finally{
	    		
	    		if(stmt != null){
	    			
	    			stmt.close();
	    			
	    		}
	    		if(dbConnection != null){
	    			
	    			dbConnection.close();
	    			
	    		}
	    	}
	    }
}

OUTPUT
Displaying records for last row
ID : 5
GMAIL : naveen
YAHOO : naveenrockz

Displaying records for first row
ID : 1
GMAIL : vinothvino
YAHOO : vinothasd

Displaying records for next row
ID : 2
GMAIL : ajithvirje
YAHOO : ajith234


Please make me understand.....

[Paul Clapham]

Both code samples look the same to me... perhaps you could check to see whether you posted what you meant to post? They could be different, but it's very hard for a reader to compare the two.

Anyway both of them should be throwing an exception at line 41, where you try to use data from a row when you haven't set a row yet. Was that what you meant when you said "doesn't work"? It would help in future if you explained in more detail what your problem was.

[John Smithonian]

I think on Code Sample 2, he meant to comment out line 41, but forgot to.

So Code Sample 1 won't work as explained - before you can use a ResultSet, you have to do a next() or last() or first() etc. As you haven't done any of these before line 41, you get an error as you have started using it.

If you want to show all the rows first, do a (while rs.next()) { ... }

[vinoth vino]

EDITED CODE
sorry i forgot to comment the line 41.... Here, is the program which I've documented at the line 41. Please help me

vinoth vino wrote: Now i m learning ResultSet types in java. Here, I've coded for viewing records in different ways.... At first i displayed the whole records which is in emp4 table and then i started to view these records in different manner(last,first,next) This is exactly what i am looking for but it won't display the all records which are presented in the emp4 table. See the First Program it doesn't work but if i documented the line 41(see this in Second Program) it just working awesome.... What's the problem ? is there any wrong with my code ???

CODE SAMPLE 1

package demojdbc;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.Statement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class MysqlCon{
	
	private static final String DB_DRIVER = "com.mysql.jdbc.Driver";
	private static final String DB_CONNECTION = "jdbc:mysql://localhost:3306/vinoth";
	private static final String DB_USER = "root";
	private static final String DB_PASSWORD = "vino";
	
	    public static void main(String args[])throws SQLException{
	    	
	    	//Creating statement and connection 
	    	Connection dbConnection = null;
	    	Statement stmt = null;
	    	
	    	try{
	    		
	    		//Creating class driver
	    		Class.forName(DB_DRIVER);
	    		
	    		//Creating Database Connection
	    		dbConnection = DriverManager.getConnection(DB_CONNECTION,DB_USER,DB_PASSWORD);
	    		
	    		//Creating statement
	    		stmt = dbConnection.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,ResultSet.CONCUR_READ_ONLY);
	    		
	    		//Creating query
	    		String sql = "SELECT id,gmail,yahoo from emp4";
	    		
	    		//Creating ResultSet
	    		ResultSet rs = stmt.executeQuery(sql);
	    		
	    		//Displaying database
	    		System.out.println("Displaying records before doing some operations");
	    		System.out.println(rs.getInt(1)+" "+rs.getString(2)+" "+rs.getString(3));
	    		
	    		System.out.println("Displaying records for last row");
	    		rs.last();
	    		
	    		int id = rs.getInt("id");
	    		String gmail = rs.getString("gmail");
	    		String yahoo = rs.getString("yahoo");
	    		
	    		//Displaying records in last row
	    		System.out.println("ID : "+id);
	    		System.out.println("GMAIL : "+gmail);
	    		System.out.println("YAHOO : "+yahoo);
	    		
	    		System.out.println();
	    		rs.first();
	    		System.out.println("Displaying records for first row");
	    		
	    		id = rs.getInt("id");
	    		gmail = rs.getString("gmail");
	    		yahoo = rs.getString("yahoo");
	    		
	    		//Displaying records in last row
	    		System.out.println("ID : "+id);
	    		System.out.println("GMAIL : "+gmail);
	    		System.out.println("YAHOO : "+yahoo);
	    		
	    		System.out.println();
	    		rs.next();
	    		System.out.println("Displaying records for next row");
	    		
	    		id = rs.getInt("id");
	    		gmail = rs.getString("gmail");
	    		yahoo = rs.getString("yahoo");
	    		
	    		//Displaying records in last row
	    		System.out.println("ID : "+id);
	    		System.out.println("GMAIL : "+gmail);
	    		System.out.println("YAHOO : "+yahoo);
	    		
	    	}catch(SQLException e){
	    		
	    		e.printStackTrace();
	    		
	    	}catch(ClassNotFoundException e){
	    		
	    	     System.out.println("Plese check the driver class path "+e.getMessage());
	    		
	    	}finally{
	    		
	    		if(stmt != null){
	    			
	    			stmt.close();
	    			
	    		}
	    		if(dbConnection != null){
	    			
	    			dbConnection.close();
	    			
	    		}
	    	}
	    }
}

Here, the code will works fine.....

CODE SAMPLE 2

package demojdbc;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.Statement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class MysqlCon{
	
	private static final String DB_DRIVER = "com.mysql.jdbc.Driver";
	private static final String DB_CONNECTION = "jdbc:mysql://localhost:3306/vinoth";
	private static final String DB_USER = "root";
	private static final String DB_PASSWORD = "vino";
	
	    public static void main(String args[])throws SQLException{
	    	
	    	//Creating statement and connection 
	    	Connection dbConnection = null;
	    	Statement stmt = null;
	    	
	    	try{
	    		
	    		//Creating class driver
	    		Class.forName(DB_DRIVER);
	    		
	    		//Creating Database Connection
	    		dbConnection = DriverManager.getConnection(DB_CONNECTION,DB_USER,DB_PASSWORD);
	    		
	    		//Creating statement
	    		stmt = dbConnection.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,ResultSet.CONCUR_READ_ONLY);
	    		
	    		//Creating query
	    		String sql = "SELECT id,gmail,yahoo from emp4";
	    		
	    		//Creating ResultSet
	    		ResultSet rs = stmt.executeQuery(sql);
	    		
	    		//Displaying database
	    		System.out.println("Displaying records before doing some operations");
	    		//System.out.println(rs.getInt(1)+" "+rs.getString(2)+" "+rs.getString(3));
	    		
	    		System.out.println("Displaying records for last row");
	    		rs.last();
	    		
	    		int id = rs.getInt("id");
	    		String gmail = rs.getString("gmail");
	    		String yahoo = rs.getString("yahoo");
	    		
	    		//Displaying records in last row
	    		System.out.println("ID : "+id);
	    		System.out.println("GMAIL : "+gmail);
	    		System.out.println("YAHOO : "+yahoo);
	    		
	    		System.out.println();
	    		rs.first();
	    		System.out.println("Displaying records for first row");
	    		
	    		id = rs.getInt("id");
	    		gmail = rs.getString("gmail");
	    		yahoo = rs.getString("yahoo");
	    		
	    		//Displaying records in last row
	    		System.out.println("ID : "+id);
	    		System.out.println("GMAIL : "+gmail);
	    		System.out.println("YAHOO : "+yahoo);
	    		
	    		System.out.println();
	    		rs.next();
	    		System.out.println("Displaying records for next row");
	    		
	    		id = rs.getInt("id");
	    		gmail = rs.getString("gmail");
	    		yahoo = rs.getString("yahoo");
	    		
	    		//Displaying records in last row
	    		System.out.println("ID : "+id);
	    		System.out.println("GMAIL : "+gmail);
	    		System.out.println("YAHOO : "+yahoo);
	    		
	    	}catch(SQLException e){
	    		
	    		e.printStackTrace();
	    		
	    	}catch(ClassNotFoundException e){
	    		
	    	     System.out.println("Plese check the driver class path "+e.getMessage());
	    		
	    	}finally{
	    		
	    		if(stmt != null){
	    			
	    			stmt.close();
	    			
	    		}
	    		if(dbConnection != null){
	    			
	    			dbConnection.close();
	    			
	    		}
	    	}
	    }
}

OUTPUT
Displaying records for last row
ID : 5
GMAIL : naveen
YAHOO : naveenrockz

Displaying records for first row
ID : 1
GMAIL : vinothvino
YAHOO : vinothasd

Displaying records for next row
ID : 2
GMAIL : ajithvirje
YAHOO : ajith234


Please make me understand.....

[vinoth vino]

Paul Clapham wrote:Both code samples look the same to me... perhaps you could check to see whether you posted what you meant to post? They could be different, but it's very hard for a reader to compare the two.

Anyway both of them should be throwing an exception at line 41, where you try to use data from a row when you haven't set a row yet. Was that what you meant when you said "doesn't work"? It would help in future if you explained in more detail what your problem was.

I'm Sorry!! I shouldn't have done like that.Please check it again... I've changed my code with comment.

[Paul Clapham]

As far as I can see John Smithonian has provided the right answer... does his answer work for you?

[vinoth vino]

John Smithonian wrote:I think on Code Sample 2, he meant to comment out line 41, but forgot to.

So Code Sample 1 won't work as explained - before you can use a ResultSet, you have to do a next() or last() or first() etc. As you haven't done any of these before line 41, you get an error as you have started using it.

If you want to show all the rows first, do a (while rs.next()) { ... }

Thank you so much..... It works good

[vinoth vino]

Paul Clapham wrote:As far as I can see John Smithonian has provided the right answer... does his answer work for you?

Thanks for your efforts.... Now it works without any issue