Thread: OleDB connection

That's a lot of overhead to get confused. Try to keep your programs simpler while learning new things.

Code:

using System;
using System.Data.OleDb;

namespace ConsoleApplication1
{
  internal class Program
  {
    public static bool ValidateUser(string password, string username)
    {
      const string connectionString = "Provider=MSDAORA;Data Source=xe;Persist Security Info=True;User ID=GOL;Password=kaRkaRr0t";
      const string sql = "SELECT COUNT(*) FROM USERLOGIN WHERE USERNAME = @name AND PASSWORD = @password";

      using (var connection = new OleDbConnection(connectionString))
      {
        using (var command = new OleDbCommand(sql, connection))
        {
          command.Parameters.AddWithValue("@name", username);
          command.Parameters.AddWithValue("@password", password);

          return Convert.ToInt32(command.ExecuteScalar()) > 0;
        }
      }
    }

    public static void Main(string[] args)
    {
      const string user = "test";
      const string password = "secret";

      bool isValid = ValidateUser(password, user);

      Console.WriteLine("{0}/{1} is {2}", user, password, isValid ? "valid" : "invalid");
    }
  }
}

I couldn't test it here, but it should demostrate what steps you have to take to authenticate somebody.