Sent mail every time there is an insert

Basically you need to control 2 things: When you open the form and when you fill the datagridView. And for this, I have created 2 variables at the form level called cargaInicial(by default, false) and registrosActuales, which will be responsible for saving the records that we currently have in the datagridView.

Therefore:

• cargaInicialwill take care of not sending an email when we are opening the form, since we are filling the datagridView for the first time.

• registrosActualescontrols the number of current records in the datagridView. If it changes and is less than the records that come from the BBDD, we will send an email and assign the new value. In this way, the next time the timer is triggered, if there is no news, it will not send any mail.

using System;
using System.Data;
using System.Data.SqlClient;
using System.Net;
using System.Net.Mail;
using System.Timers;
using System.Windows.Forms;

namespace AlertaPDC
{
    public partial class Form1 : Form
    {
        private static System.Timers.Timer aTimer;
        private SqlCommand Comando = new SqlCommand();
        private SqlDataReader LeerFilas;

        private bool cargaInicial = false;
        private int registrosActuales = 0;

        public Form1()
        {
            InitializeComponent();
            ListarTraslados();
            cargaInicial = true;
            SetTimer();
        }

        private SqlConnection Connection()
        {
            return new SqlConnection("Server=192.168.1.; Password=S0p0rt3;user=sa;DataBase=PRU");
        }

        public DataTable ListarPDC()
        {
            SqlConnection conexion = Connection();
            DataTable Tabla = new DataTable();
            conexion.Open();
            Comando.Connection = conexion;
            Comando.CommandText = "SP_ALERTAPDC";
            Comando.CommandType = CommandType.StoredProcedure;
            LeerFilas = Comando.ExecuteReader();

            // Si no es la carga inicial y el nº de registros actuales es inferior a los devueltos, quiere decir que se ha añadido un registro
            // Por lo tanto, envío un email y guardo el nuevo valor en la variable registrosActuales
            if (!cargaInicial && registrosTotales < LeerFilas.count){
                Envio();
                registrosTotales = LeerFilas.count;
            }

            Tabla.Load(LeerFilas);
            LeerFilas.Close();
            conexion.Close();
            return Tabla;
        }

        public void ListarTraslados()
        {
            dataGridView1.DataSource = ListarPDC();
        }


        private void SetTimer()
        {
            aTimer = new System.Timers.Timer(5000);
            aTimer.Elapsed += OnTimedEvent;
            aTimer.AutoReset = true;
            aTimer.Enabled = true;
        }


        private void OnTimedEvent(Object source, ElapsedEventArgs e)
        {
            Invoke((MethodInvoker)ListarTraslados);
        }


        private void Envio() 
        {
            SmtpClient client = new SmtpClient("smtp.gmail.com", 587);
            MailMessage message = new MailMessage("[email protected]", "[email protected]", "RESOLUCION DE FACTURACION CREDITO PROXIMA A VENCER", "La resolucion de facturacion  de el punto de venta X, Consecutivos restantes: " + resolucionFa);
            //Si tu servidor smtp necesita credenciales, las pones asi
            client.EnableSsl = true;
            client.Credentials = new NetworkCredential("[email protected]", "Sopor19*");
            //Finalmente envias el mensaje
            client.Send(message);

        }
    }
}