SqlCommand sqlCmd = new SqlCommand("ProductosCreateOrUpdate", cn);
sqlCmd.CommandType = CommandType.StoredProcedure;
sqlCmd.Parameters.AddWithValue("@id", (hfProductoID.Value == "" ? 0 : Convert.ToInt32(hfProductoID.Value)));
sqlCmd.Parameters.AddWithValue("@descripcion", txtDescripcion.Text.Trim());
sqlCmd.Parameters.AddWithValue("@idmarca", Convert.ToInt32(ddlMarca.SelectedValue?.Trim()));
sqlCmd.Parameters.AddWithValue("@idcategoria", Convert.ToInt32(ddlCategoria.SelectedValue?.Trim()));
sqlCmd.Parameters.AddWithValue("@existencia", Convert.ToInt32(txtExistencia.Text.Trim()));
sqlCmd.Parameters.AddWithValue("@precioA", float.Parse(txtprecioA.Text.Trim()));
sqlCmd.Parameters.AddWithValue("@precioB", float.Parse(txtpreciob.Text.Trim()));
sqlCmd.Parameters.AddWithValue("@precioC", float.Parse(txtprecioc.Text.Trim()));
sqlCmd.Parameters.AddWithValue("@precioD", float.Parse(txtpreciod.Text.Trim()));
sqlCmd.ExecuteNonQuery();
cn.Close();