title: The SqlParameterCollection only accepts non-null SqlParamter type objects, not String objects
body: <pre><code>SqlCommand cmd = con.CreateCommand();
  cmd.CommandText = "INSERT INTO Records ([Student ID], [First Name], [Last Name], " + 
                    "[Middle Initial], Gender, Address, Status, Year, Email, Course, " + 
                    "[Contact Number]) VALUES ( @Student ID,  @First Name, @Last Name, " + 
                    "@Middle Initial, @Gender, @Address, @Status, @Year, @Email, " + 
                    "@Course, @Contact Number)";
  
          SqlParameter p1 = new SqlParameter("@[Student ID]", SqlDbType.Int);
          p1.Value = textBox1.Text;
          cmd.Parameters.Add("1");
          SqlParameter p2 = new SqlParameter("@First Name", SqlDbType.VarChar);
          p2.Value = textBox2.Text;
          cmd.Parameters.Add("p2");
          SqlParameter p3 = new SqlParameter("@Last Name", SqlDbType.NVarChar);
          p3.Value = textBox3.Text;
          cmd.Parameters.Add("p3");
          SqlParameter p4 = new SqlParameter("@Middle Initial", SqlDbType.NChar);
          p4.Value = comboBox1.Text;
          cmd.Parameters.Add("p4");
          SqlParameter p5 = new SqlParameter("@Gender", SqlDbType.NChar);
          p5.Value = comboBox2.Text;
          cmd.Parameters.Add("p5");
          SqlParameter p6 = new SqlParameter("@Address", SqlDbType.VarChar);
          p6.Value = textBox4.Text;
          cmd.Parameters.Add("p6");
          SqlParameter p7 = new SqlParameter("@Status", SqlDbType.NChar);
          p7.Value = comboBox3.Text;
          cmd.Parameters.Add("p7");
          SqlParameter p8 = new SqlParameter("@Year", SqlDbType.VarChar);
          p8.Value = comboBox4.Text;
          cmd.Parameters.Add("p8");
          SqlParameter p9 = new SqlParameter("@Email", SqlDbType.VarChar);
          p9.Value = textBox5.Text;
          cmd.Parameters.Add("9");
          SqlParameter p10 = new SqlParameter("@Course", SqlDbType.VarChar);
          p10.Value = comboBox5.Text;
          cmd.Parameters.Add("p10");
          SqlParameter p11 = new SqlParameter("@Contact Number", SqlDbType.VarChar);
          p11.Value = textBox6.Text;
          cmd.Parameters.Add("p11");
  
          cmd.ExecuteNonQuery();
          con.Close();
  </code></pre>