Ошибка system.data.sqlclient.sqlexception. неверный синтаксис

Question

В настоящее время я делаю страницу регистрации учетной записи, но получаю сообщение об ошибке system.data.sqlclient.sqlexception. неверный синтаксис рядом с адресом. Что не так с кодировкой?

protected void Page_Load(object sender, EventArgs e)
    {
        if(IsPostBack)
        {
            SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["RegistrationConnectionString"].ConnectionString);
            conn.Open();
            string checkuser = "select count(*) from [UserData] where UserName='" + TextBoxUN.Text + "'";
            SqlCommand com = new SqlCommand(checkuser, conn);
            int temp = Convert.ToInt32(com.ExecuteScalar().ToString());
            if (temp ==1)
            {
                MessageBox.Show("User Already Exists.");
            }

            conn.Close();
        }
    }

    protected void Button1_Click(object sender, EventArgs e)
    {
        try
        {
            SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["RegistrationConnectionString"].ConnectionString);
            conn.Open();
            string insertQuery = "insert into [UserData] (Username,Email Address,Password,Phone Number,Full Name,Home Address) values (@Username,@EmailAddress,@Password,@PhoneNumber,@FullName,@HomeAddress)";
            SqlCommand com = new SqlCommand(insertQuery, conn);
            com.Parameters.AddWithValue("@Username", TextBoxUN.Text);
            com.Parameters.AddWithValue("@EmailAddress", TextBoxEmail.Text);
            com.Parameters.AddWithValue("@Password", TextBoxPass.Text);
            com.Parameters.AddWithValue("@PhoneNumber", TextBoxPhone.Text);
            com.Parameters.AddWithValue("@FullName", TextBoxFull.Text);
            com.Parameters.AddWithValue("@HomeAddress", TextBoxHome.Text);

            com.ExecuteNonQuery();
            Response.Redirect("Manager.aspx");
            MessageBox.Show("Registration is successful!");
            conn.Close();
        }
        catch (Exception ex)
        {
            MessageBox.Show("Error:"+ ex.ToString());
        }
    }