Login

SqlCeConnection con = new SqlCeConnection("Data Source=\"" + System.IO.Path.Combine(Application.StartupPath, "Info.sdf") + "\"");
        public login()
        {
            InitializeComponent();

        }

        bool status = true;
        private void login_btn_Click(object sender, EventArgs e)
        {
            try
            {
                if(status == true)
                    con.Open();
                status = false;

                if (username.Text == "" || password.Text == "")
                {
                    MessageBox.Show("Enter Username and Password");
                    return;
                }

                //string query = ;

                SqlCeCommand cmd = new SqlCeCommand("SELECT * FROM 'user' WHERE username=@username AND password=@pass", con);
                cmd.Parameters.AddWithValue("@username", username.Text);
                cmd.Parameters.AddWithValue("@pass", password.Text);

                SqlCeDataAdapter da = new SqlCeDataAdapter(cmd);
                DataTable dt = new DataTable();
                da.Fill(dt);
                dataGridView1.DataSource = dt;

                //MessageBox.Show(dt.Rows.Count.ToString());

                if (dt.Rows.Count > 0)
                {
                    MessageBox.Show("Ok");
                }
                else
                    MessageBox.Show("Invalid");
            }
            catch (SqlCeException ex)
            {

                MessageBox.Show(ex.Message);
            }


        }