QUERY FOR DATE AND TIME SLOT

Select to_char((To_Date(Decode('01/MAY/2013', '', '01/Jan/1910', '01/MAY/2013') ||
                ' 0001',
                'DD-MON-YYYY HH24MI')) + (Rownum - 1) / 24 ,'DD-MON-YYYY HH:MI:SS AM') FromDate,
       to_char((To_Date(Decode('31/MAY/2013', '', '31/Dec/9990', '31/MAY/2013') ||
                ' 0000',
                'DD-MON-YYYY HH24MI')) + (Rownum / 24),'DD-MON-YYYY HH:MI:SS AM') ToDate,
       'F' Type,
       'XXXX' Operator,
       '' FlightNature
  From tab
 Where Rownum <= 24