Base types (int, bit, double, etc) - How to allow NULL

By adding a question mark after the base type it allows it to pass nulls. See example below.

ASPX.CS

            
int? sessionId = null;  
if (ddlSessionFilter.SelectedValue.ToString() != "Show all")
{
	sessionId = int.Parse(ddlSessionFilter.SelectedValue.ToString());
}

gvRecipients.DataSource = Recipient.RecipientReport(attending, sessionId);
gvRecipients.DataBind();

APP_Code > FileName.CS

            

    public static DataSet RecipientReport(int attending, int? sessionId)
    {
        DataSet oDataSet = new DataSet();
        using (SqlConnection oSqlConnection = new SqlConnection(ConfigSettings.SqlServerConnectionString()))
        {
            SqlCommand oSqlCommand = new SqlCommand("CustomerFocusRecipientReport", oSqlConnection);
            oSqlCommand.CommandType = CommandType.StoredProcedure;
            oSqlCommand.Parameters.Add("@Attending", SqlDbType.Int, 4).Value = attending;

            if (sessionId != null)
            {
                oSqlCommand.Parameters.Add("@SessionId", SqlDbType.Int, 4).Value = sessionId;
            }

            SqlDataAdapter oSqlDataAdapter = new SqlDataAdapter(oSqlCommand);
            oSqlDataAdapter.Fill(oDataSet, "Report");
        }

        return oDataSet;

    }