ถ้าต้องการเช็ค id และ pass ของ win form จะต้องทำยังไงมีตัวอย่างด้านใน

            strConnString = "Server=localhost;UID=sa;PASSWORD=;Database=mydatabase;Max Pool Size=400;Connect Timeout=600;";
            objConn.ConnectionString = strConnString;
            objConn.Open();

            int intNumRows = 0;
            strSQL = "SELECT COUNT(*) FROM member WHERE Username = '" + this.txtUsername.Text + "' AND Password = '" + this.txtPassword.Text + "' ";
            objCmd = new SqlCommand(strSQL, objConn);
            intNumRows = Convert.ToInt32(objCmd.ExecuteScalar());

            if (intNumRows > 0)
            {
                frmMain frm = new frmMain();
                frm._strUser = this.txtUsername.Text;
                frm.LoadInfor();
                frm.Show();

                this.Hide();
            }
            else
            {
                MessageBox.Show("Username or Password Incorrect");
            }

            objConn.Close();
            objConn = null;

<connectionStrings>
        <add name="WindowsFormsApplication1.Properties.Settings.Database1ConnectionString"
            connectionString="Data Source=|DataDirectory|\Database1.sdf"
            providerName="Microsoft.SqlServerCe.Client.3.5" />
    </connectionStrings>

string directory = Path.GetDirectoryName(Application.ExecutablePath);


            strConnString = "providerName=Microsoft.SqlServerCe.Client.3.5;Data Source=" + directory + "\\Database1.sdf;Jet OLEDB:Database Password=;";
            objConn.ConnectionString = strConnString;
            objConn.Open();

            strConnString = "Provider=Microsoft.SqlServerCe.Client.3.5; Data Source=Data Source =C:\\Users\\supavichsur\\documents\\visual studio 2010\\Projects\\WindowsFormsApplication1\\WindowsFormsApplication1\\Database1.sdf";
            objConn.ConnectionString = strConnString;
            objConn.Open();