Query to get data less than date

private Query buildQuery(Query _query,StartDate _date)
{
    if(!tDate)
        tDate = systemDateGet();
    if(tDate)
    {
        _query.dataSourceTable(tablenum(DNemplContract)).addRange(fieldnum(DNemplContract, StartDate)).value(strFmt("<= %1", tDate));
      //  _query.dataSourceTable(tablenum(DNemplContract)).addRange(fieldnum(DNemplContract, //StartDate)).value(queryValue(tDate));
   
    }
        return _query;
}