unexpected output

[Amritpal Singh Moomie]

HI I am trying to create a user check method by accessing database for my jsf application.
Can anybody tell me why i am getting login (i.e success output ) from code even when i enter wrong loginname and password?

public String CheckValidUser()
{
	
	String query = "SELECT * FROM users WHERE name = ? and pass = ?";
	String result=" ";
	try
	{    Class.forName("com.mysql.jdbc.Driver").newInstance();
		 String url = "jdbc:mysql://localhost/moh";
		 conn = DriverManager.getConnection(url, " ", " ");
		 PreparedStatement prepStmt = conn.prepareStatement(query);
		 prepStmt.setString(1, loginname);
		 prepStmt.setString(2, password);
		 ResultSet rs = prepStmt.executeQuery();
		 
		 if (rs==null)
		 {
		  result ="fail";
		 }
		else if(rs!=null)
		{
		 result ="success";
		}
		 
		 
		 conn.close();
		
	}
	 
	
	catch (ClassNotFoundException ex) {System.err.println(ex.getMessage());}
    catch (IllegalAccessException ex) {System.err.println(ex.getMessage());}
    catch (InstantiationException ex) {System.err.println(ex.getMessage());}
    catch (SQLException ex)           {System.err.println(ex.getMessage());}   
  
   return result;
   
}

[Amritpal Singh Moomie]

I am trying to check whether the resultset is null or not?
If its null that is there is no record like that means fail (no login)
and if its not null that is success( successfull login)

[Paul Sturrock]

ResultSets are never null. They are empty sometimes though...

[Amritpal Singh Moomie]

so how can i check that there is no record for that query?
or it is empty

[Paul Sturrock]

Have a look at the ResultSet JavaDocs. You should see the method available to you. Alternatively you could change your sql to count the number of users that match your search criteria and check that.

[Amritpal Singh Moomie]

thanks for the help
I figured out how to do it

rs = ...  
   
if (rs.next()) {  
        // here you know that there is at least one record, which is what your question was about  
   do {  
        // here you do whatever needs to be done for each record. Note that it will be called for the first record.  
    } while (rs.next());  
} else {  
    // here you do whatever needs to be done when there is no record  
}