[C#] Actualizare informatii baza de date in timpul utilizarii aplicatiei

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace Olimpiada2016 {
public partial class frmStart : Form {
	 public frmStart() {
		 InitializeComponent();
	 }
	 private void btnInregistrare_Click(object sender, EventArgs e) {
		 frmInregistrare inregistrare = new frmInregistrare();
		 inregistrare.Show();
	 }
	 private void btnAutentificare_Click(object sender, EventArgs e) {
		 frmAutentificare autentificare = new frmAutentificare();
		 autentificare.Show();
	 }
}
}

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Configuration;
using System.Data.SqlClient;
using System.Net.Mail;

namespace Olimpiada2016 {
public partial class frmInregistrare : Form {
	 string connectionString;
	 public frmInregistrare() {
		 InitializeComponent();
		 connectionString = ConfigurationManager.ConnectionStrings["Olimpiada2016.Properties.Settings.GOOD_FOODConnectionString"].ConnectionString;
	 }

	 private bool isValidEmail(string email) {
		 try {
			 var addr = new System.Net.Mail.MailAddress(email);
			 return addr.Address == email;
		 } catch {
			 return false;
		 }
	 }

	 private void btnInregistrare_Click(object sender, EventArgs e) {
		 if (!isValidEmail(txtEmail.Text)) {
			 MessageBox.Show("Adresa de email nu este valida.", "Eroare");
		 } else if (txtParola.Text != txtReintroducereParola.Text) {
			 MessageBox.Show("Parolele nu coincid.", "Eroare");
			 txtParola.Text = "";
			 txtReintroducereParola.Text = "";
		 } else {
			 using (SqlConnection connection = new SqlConnection(connectionString))
			 using (SqlCommand command = new SqlCommand("SELECT COUNT(*) FROM Clienti WHERE email = @emailCheck", connection)) {
				 connection.Open();
				 command.Parameters.AddWithValue("@emailCheck", txtEmail.Text);
				 int t = (int)command.ExecuteScalar();
				 if (t == 1) {
					 MessageBox.Show("Exista deja un user cu aceasta adresa de email", "Eroare");
				 } else {
					 command.CommandText = "INSERT INTO Clienti (parola, nume, prenume, adresa, email, kcal_zilnice) VALUES (@parola, @nume, @prenume, @adresa, @email, @kcal_zilnice)";
					 command.Parameters.AddWithValue("@parola", txtParola.Text);
					 command.Parameters.AddWithValue("@nume", txtNume.Text);
					 command.Parameters.AddWithValue("@prenume", txtPrenume.Text);
					 command.Parameters.AddWithValue("@adresa", txtAdresa.Text);
					 command.Parameters.AddWithValue("@email", txtEmail.Text);
					 command.Parameters.AddWithValue("@kcal_zilnice", 1);
					 command.ExecuteNonQuery();
					 MessageBox.Show("Inregistrare efectuata cu succes!", "Bun venit");
					 this.Close();
				 }
			 }
		 }
	 }
}
}

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Configuration;
using System.Data.SqlClient;

namespace Olimpiada2016 {
public partial class frmAutentificare : Form {
	 string connectionString;
	 public frmAutentificare() {
		 InitializeComponent();
		 connectionString = ConfigurationManager.ConnectionStrings["Olimpiada2016.Properties.Settings.GOOD_FOODConnectionString"].ConnectionString;
	 }
	 private void btnAutentificare_Click(object sender, EventArgs e) {
		 using (SqlConnection connection = new SqlConnection(connectionString))
		 using (SqlCommand command = new SqlCommand("SELECT COUNT(*) FROM Clienti WHERE email = @emailCheck AND parola = @parolaCheck", connection)) {
			 connection.Open();
			 command.Parameters.AddWithValue("@emailCheck", txtEmail.Text);
			 command.Parameters.AddWithValue("@parolaCheck", txtParola.Text);
			 int t = (int)command.ExecuteScalar();
			 if (t == 1) {
				 MessageBox.Show("Da");
			 } else {
				 MessageBox.Show("Eroare autentificare", "Eroare");
				 txtParola.Text = "";
				 txtEmail.Text = "";
			 }
		 }
	 }
}
}