C#

ERROR:-No mapping exists from object type System.Data.DataRowView to a known managed provider native type.

SmtpClient client = new SmtpClient();
            client.Port = 587;
            client.Host = "smtp.gmail.com";
            client.EnableSsl = true;
            
            MailMessage mail = new MailMessage(new MailAddress("smanghnani23@gmail.com"), new MailAddress(TextBox2.Text));
            MailMessage mail1 = new MailMessage(new MailAddress("smanghnani23@gmail.com"), new MailAddress("smanghnani23@gmail.com"));
            mail.Subject = "Thank You For Submitting Your Request";
            mail1.Subject = "A New HIRING Request is Generated";
            mail1.Body = TextBox3.Text;
            mail.Body = "Thank you for registering with us";
            System.Net.NetworkCredential cred = new System.Net.NetworkCredential();
            cred.UserName = "smanghnani23@gmail.com";
            cred.Password = "password";
            client.Credentials = cred;
            client.Send(mail);
            client.Send(mail1);
            Label3.Visible = true;
            Label3.Text = "Send Succesfully";

try
 {
    // for MainTable ...
    OleDbConnection cnnSave=new OleDbConnection(myConnection);
    OleDbCommand cmd__AddRows = new OleDbCommand();
    cmd__AddRows.CommandText =
    @"INSERT INTO MainRegTable (IDMetal,NameMetal,FormulMetal, GroupMetal, CodeMetal,Comments)
    VALUES (@p1,@p2,@p3,@p4,@p5,@p6)";
    cmd__AddRows.Parameters.Clear();
    cmd__AddRows.Parameters.AddWithValue("@p1", txtID.Text);
    ....
   //for subTable ...
     OleDbDataAdapter dagrd = new OleDbDataAdapter(@"Select * From SubTblMetal
                                                    WHERE IDMetal=
                                                    "+int.Parse(txtID.Text),
                                                           cnnSave);
      DataSet dsGrd = new DataSet();
      dagrd.Fill(dsGrd, "SubTblMetal");
      dsGrd.GetChanges();
      dagrd.Update(dsGrd);
      dsGrd.AcceptChanges();