C# Programlama Dilinde Kayıt Ekleme

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Data.SqlClient;

namespace WindowsApplication1
{
public partial class Form1 : Form
{SqlConnection conn;
SqlCommand cmd;
public Form1()
{
InitializeComponent();
}

private void Form1_Load(object sender, EventArgs e)
{
conn = new SqlConnection();
conn.ConnectionString = @"Data Source=.\SQLEXPRESS;AttachDbFilename=C:\ticaret.mdf;Integrated Security=True;Connect Timeout=30;User Instance=True";
conn.Open();

kayitsayisi();

}
public void kayitsayisi()
{
SqlCommand cmd = new SqlCommand();
cmd.Connection = conn;
cmd.CommandText = "SELECT Count(*) FROM musteriler";
label6.Text = "Kayıt Sayısı:" + cmd.ExecuteScalar().ToString();
}

private void button1_Click(object sender, EventArgs e)
{
SqlCommand cmd = new SqlCommand();
cmd.Connection = conn;
cmd.CommandText = @"
INSERT INTO musteriler
(must_ad,must_kontak,must_sehir,must_ulke)
VALUES
(@ad,@kontak,@sehir,@ulke)
";
cmd.Parameters.AddWithValue("@ad",textBox1.Text);
cmd.Parameters.AddWithValue("@kontak",textBox2.Text);
cmd.Parameters.AddWithValue("@sehir",textBox3.Text);
cmd.Parameters.AddWithValue("@ulke",textBox4.Text);
//çalıştır
cmd.ExecuteNonQuery();
kayitsayisi();
MessageBox.Show("Kayıt Başarıyla Tamamlandı");

}
}
}