Date_format and order by date problem

Question

Hi,
I have a problem with taking the resultset as sorted by date.
example1:
SELECT
T.foreign_network_id as "Network ID",
                         date_format(T.ARRIVAL_DATE,'%d-%m-%Y') as "Date",
                    sum(case when((networks_rejected = 0)
                                   and (T.sor_reapply = 'N')
                                   and (T.sor_reason in ('NP', 'NU', 'NT', 'HT')))
                                   then T.CNT else 0 end) as "Before Steering",
               sum(case when(sor_reason in ('NP', 'HT', 'T2', 'TM', 'NM', 'MM', 'IPMM', 'NPMM'))
                              then T.CNT else 0 end) as "After Steering"
          FROM     ST_INC T,
                    NETWORKS N,
                    ZONE_NW_MAP ZN,
                    ZONES Z,
                    PAYMENT_TYPE PT
          WHERE      T.FOREIGN_NETWORK_ID = N.NETWORK_ID
          AND      ZN.NETWORK_ID = N.NETWORK_ID
          AND      Z.ZONE_ID = ZN.ZONE_ID
          AND      PT.id = T.ptype
          AND opcode = 2
          AND      sor_action is not null
                         and Z.ZONE_ID = 269
               group by
                         date_format(T.ARRIVAL_DATE,'%d-%m-%Y'),
T.foreign_network_id
order by      date_format(T.ARRIVAL_DATE,'%d-%m-%Y')
There is no problem with example 1 however it sorts the result set as if the date field is a string. I know this should be because I use date_format with order by. When I delete and only use T.ARRIVAL_DATE, I get "not a group by expression" error. And the reason why I use date_format is that sometimes I want to retrieve different format such as '%m-%Y' or only '%Y'. So I am required to use date_format, but then I lose the chance to sort by the actual date. I tried to select "T.ARRIVAL_DATE" as another extra colum and sort with respect to that. But this time I lost tha chance to select it again in the date_format function. Can anybody help me, I am messed up here?
Edited by: user13378594 on Aug 26, 2010 3:00 PM

Answer 1

user11268895 wrote:
... you are in an PL/SQL forum not in a mysql forum.
if you want we can translate your query in a Oracle DB query...Well... MySql is an Oracle Database...
to the op:
If you want to order then you need an ORDER BY clause at the end of your statement.
Instead of date_format you can use TO_DATE if dealing if strings. If it is a datatype date, then there is no need of a conversion.
group by T.ARRIVAL_DATE, T.foreign_network_id
order by t.arrival_date descyou could also group on the day or the month if that is what you want.
day groups
select trunc(T.ARRIVAL_DATE), ...
group by trunc(T.ARRIVAL_DATE), T.foreign_network_id
order by trunc(T.ARRIVAL_DATE) desc;
month groups
select trunc(T.ARRIVAL_DATE,'mm'), ...
group by trunc(T.ARRIVAL_DATE,'mm'), T.foreign_network_id
order by trunc(T.ARRIVAL_DATE,'mm') desc;
boy groups
select trunc(T.ARRIVAL_DATE,'boy'), ...
group by trunc(T.ARRIVAL_DATE,'boy'), T.foreign_network_id
order by trunc(T.ARRIVAL_DATE,'boy') desc;
/* Ok, ignore the last one, I was just testing if you read until the end. */ Edited by: Sven W. on Aug 26, 2010 2:25 PM