为什么这些代码工作，但不添加记录到我的数据库

SqlConnection conn = new SqlConnection();
conn.ConnectionString = @"Data Source=CASPER_NIRVANA\FARID;Initial Catalog=proje;Integrated Security=True";
SqlCommand cmd = new SqlCommand();
cmd.Connection = conn;
cmd.CommandText = "INSERT INTO projetablosu(basvuru_no)VALUES(@basvuru_no)";
cmd.Parameters.AddWithValue("basvuru_no", textBox1.Text);
cmd.ExecuteNonQuery();
SqlConnection conn = new SqlConnection();
conn.