How to insert NULL for INTEGER data type in SQL Server from C# .Net

This code will insert Null value in Int data type column

C#

protected void Save(object sender, EventArgs e)
{
    int no = 0;
    string constr = ConfigurationManager.ConnectionStrings["Constr"].ConnectionString;
    using (SqlConnection con = new SqlConnection(constr))
    {
        string query = "insert into tblCheckIn values (@Number)";
        using (SqlCommand cmd = new SqlCommand(query))
        {
            cmd.Connection = con;
            if (no == 0)
            {
                cmd.Parameters.AddWithValue("@Number", DBNull.Value);
            }
            else
            {
                cmd.Parameters.AddWithValue("@Number", no);
            }
            con.Open();
            cmd.ExecuteNonQuery();
            con.Close();
        }
    }
}

SQL