Error in retrieving data from SQL table :

[mail2sakthi2003]

Hi,
Iam a begginer and i tried to establish the connection with my SQL DB through JAVA. The connection got established but i could not retrieve the data through the query. Could you check and tell whethr the query is correct. thank you.

here is the program::

Class.forName("sun.jdbc.odbc.JdbcOdbcDriver").newI nstance();
String url = "jdbc:odbc:sakthi";
con = (Connection)DriverManager.getConnection(url,"sakth i","");
Statement stmt=con.createStatement();
System.out.println("Connection :"+con);
System.out.println("Connection is created!"+login_name);

String run=("select * from logg where user ="+"'"+login_name+"'");-----> Is this query correct. i chked wth ony "select * from logg", i got the output. when i tried this one....it's not working. it goes to the 'catch' function.


ResultSet rs=stmt.executeQuery(run);
while(rs.next())
{

uid=rs.getString("user");
psswd=rs.getString("pass") ;
}

con.close();

[r035198x]

Hi,
Iam a begginer and i tried to establish the connection with my SQL DB through JAVA. The connection got established but i could not retrieve the data through the query. Could you check and tell whethr the query is correct. thank you.

here is the program::

Class.forName("sun.jdbc.odbc.JdbcOdbcDriver").newI nstance();
String url = "jdbc:odbc:sakthi";
con = (Connection)DriverManager.getConnection(url,"sakth i","");
Statement stmt=con.createStatement();
System.out.println("Connection :"+con);
System.out.println("Connection is created!"+login_name);

String run=("select * from logg where user ="+"'"+login_name+"'");-----> Is this query correct. i chked wth ony "select * from logg", i got the output. when i tried this one....it's not working. it goes to the 'catch' function.


ResultSet rs=stmt.executeQuery(run);
while(rs.next())
{

uid=rs.getString("user");
psswd=rs.getString("pass") ;
}

con.close();

1.) Please use code tags when posting code.
2.) Did you try to print the sql to see what it says before passing it to the executeQuery.
3.) You'll save yourslef lots of debugging if you just use a PreparedStatement for this.

[mail2sakthi2003]

Class.forName("sun.jdbc.odbc.JdbcOdbcDriver").newInstance();
String url = "jdbc:odbc:sakthi"; 
con = (Connection)DriverManager.getConnection(url,"sakthi","");
Statement stmt=con.createStatement();
System.out.println("Connection :"+con);
System.out.println("Connection is created!"+login_name);
 
String run=("select * from logg where user ="+"'"+login_name+"'");
 
/* Is this query correct. i chked wth ony "select * from logg", i got the output. when i tried this one....it's not working. it goes to the 'catch' function. */
 
 
ResultSet rs=stmt.executeQuery(run);
while(rs.next()) 
{ 
 
uid=rs.getString("user");
psswd=rs.getString("pass") ;
}
 
con.close();

i have also tried with this code...

 
while(rs.next())                        
    {   
     System.out.println(login_name);
     System.out.println(rs.getString(1));
     if(rs.getString("user").equals(login_name))
 
    {
    System.out.println("hello");     
     uid=(rs.getString(1));
     psswd=(rs.getString(2)) ;
     passt.setText(uid);
      }
 
     }
   con.close();
 
    }
        catch(Exception s)
        {
        System.out.println("Doesn't establish the connection!");
            System.exit(0);
        }

in this code, rs.getString(1), the value given in the table is "sample"
login_name-> the value given is also "sample" . but the evaluation in the "if" statement is not working. both the names given are the same but its not cheking it and entering into the if statement even both are same. plz help me out from this.

if(rs.getString("user").equals(login_name))

[r035198x]

Class.forName("sun.jdbc.odbc.JdbcOdbcDriver").newInstance();
String url = "jdbc:odbc:sakthi"; 
con = (Connection)DriverManager.getConnection(url,"sakthi","");
Statement stmt=con.createStatement();
System.out.println("Connection :"+con);
System.out.println("Connection is created!"+login_name);
 
String run=("select * from logg where user ="+"'"+login_name+"'");
 
/* Is this query correct. i chked wth ony "select * from logg", i got the output. when i tried this one....it's not working. it goes to the 'catch' function. */
 
 
ResultSet rs=stmt.executeQuery(run);
while(rs.next()) 
{ 
 
uid=rs.getString("user");
psswd=rs.getString("pass") ;
}
 
con.close();

i have also tried with this code...

 
while(rs.next())                        
    {   
     System.out.println(login_name);
     System.out.println(rs.getString(1));
     if(rs.getString("user").equals(login_name))
 
    {
    System.out.println("hello");     
     uid=(rs.getString(1));
     psswd=(rs.getString(2)) ;
     passt.setText(uid);
      }
 
     }
   con.close();
 
    }
        catch(Exception s)
        {
        System.out.println("Doesn't establish the connection!");
            System.exit(0);
        }

in this code, rs.getString(1), the value given in the table is "sample"
login_name-> the value given is also "sample" . but the evaluation in the "if" statement is not working. both the names given are the same but its not cheking it and entering into the if statement even both are same. plz help me out from this.

if(rs.getString("user").equals(login_name))

Perhaps the value in the database contains some leading or trailing spaces (use TRIM). Perhaps the case is different (use equalsIgnoreCase)

You are also violating some rules of getting data from a result set (read this thread.)

[mail2sakthi2003]

Perhaps the value in the database contains some leading or trailing spaces (use TRIM). Perhaps the case is different (use equalsIgnoreCase)

You are also violating some rules of getting data from a result set (read this thread.)

I hav tried both TRIM and IGNORECASE...but still i cant get it...but if i give [HTML]System.out.println(rs.getString(1));[/HTML]

iam able to get the data from database....but can perform the if statement. i have given the entire program and the output. can u help me out.

public void actionPerformed(ActionEvent e) 
    {  
        Connection con=null;
        String login_name=null;
 
        String uid = null;
        //String psswd = null;
        //String str=new String(passt.getPassword());
 
        if (e.getSource()== sub)
        {
            try
            {
 
                  login_name=usert.getText();
                  login_name=login_name.trim();
                  Class.forName("sun.jdbc.odbc.JdbcOdbcDriver").newInstance();
                  String url = "jdbc:odbc:sakthi"; 
                  con = (Connection)DriverManager.getConnection(url,"sakthi","");
                  Statement stmt=con.createStatement();
                  System.out.println("Connection :"+con);
                  System.out.println("Connection is created!"+login_name);
                  String run=("select * from logg");
                  ResultSet rs=stmt.executeQuery(run);
                  while(rs.next())                        
                {   
                     System.out.println(login_name);
                     System.out.println(rs.getString(1));
                     if(rs.getString("user").trim().equalsIgnoreCase(login_name.trim()))
 
                     {
                     System.out.println("hello");     
                     uid=(rs.getString(1));
                     psswd=(rs.getString(2)) ;
 
                     passt.setText(uid);
                     }
                     else
                     {
                         System.out.println(" tata");
                     }
 
                  }
                 con.close();
 
            }
                catch(Exception s)
                {
                  System.out.println("Doesn't establish the connection!");
                  System.exit(0);
                }
 
        }
        else if (e.getSource()==res)
        {
            usert.setText("");
            passt.setText("");
 
        }
    }

output is:

Connection :sun.jdbc.odbc.JdbcOdbcConnection@198dfaf
Connection is created!sakthi
sakthi
sakthi

[r035198x]

You did not do anything about the third comment I made in my post above.
Why don't you print the values using println statements and see if they match.

[mail2sakthi2003]

i have done that also. i have tried with many System.out.println() in displaying the values. Till the If Statement in the While loop(rs.next())..its working. The database is retrieved. can u chk what mistake i have made in that coding. just the coding inside the while loop(); thank you.

[r035198x]

i have done that also. i have tried with many System.out.println() in displaying the values. Till the If Statement in the While loop(rs.next())..its working. The database is retrieved. can u chk what mistake i have made in that coding. just the coding inside the while loop(); thank you.

Retrieve the value once from the resultset using getString and store it in a String variable. Every time you want to access it again just use that variable and don't call rs.getString again (you should really have a look at my third comment above).