SQL query to select row with MAX date

I'm trying to return the row with the MAX date but the MAX funciton doesn't appear to be working. Below is the code I'm trying to run along with the outputMax-query.JPG: Any help you can provide will be very much appreciated.

select doc_prfx, doc_num, BKD_WGT, BKD_VOL, ACCEPTED_PCS, ACCEPTED_VOL, sum (ACCEPTED_WGT - BKD_WGT), sum (ACCEPTED_VOL - BKD_VOL), MAX(modified_date)

from 

(Select distinct 
c.car_id,
 b.doc_prfx, b.doc_num, 

f.wt_bfr_awb as BKD_WGT, f.vol_bfr_awb as BKD_VOL,

g.num_pcs as ACCEPTED_PCS,
g.ttl_wt as ACCEPTED_WGT, g.vol as ACCEPTED_VOL,

to_char(f.modified_date,  'DD-MON-YYYY HH24:MI:SS') as modified_date

from sbh_res_itnry a, sbh_car b, sbh_res c, sbh_res_cust d, fwb_res_data_aud e, sbh_res_aud f, sbh_AWB g
where c.car_id = b.car_id (+)
and c.car_id = a.car_id 
and c.car_id = d.car_id
and b.car_id = e.car_id (+)
and c.car_id = f.car_id 
and c.car_id = g.car_id
and a.aln_code = 'VS'
and a.flt_num = '0003'
and trunc (a.dep_date) = '04-APR-2017'
--and e.rmk_typ = 'BKL' --in (null,'BKL')
AND a.cncl_ind = 'N'
and d.cust_typ = 'AGT'
and b.cncl_ind = 'N'
and c.enq_ind = 'N'
and f.wt_bfr_awb is not null
and b.doc_prfx = '932'
and b.doc_num in ('51493422')
)
group by 

doc_prfx, doc_num, BKD_WGT, BKD_VOL, ACCEPTED_PCS, ACCEPTED_VOL,modified_date

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Jason PalmerAsked:
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ste5anSenior DeveloperCommented:
To filter by that, you need a subquery. The MAX() aggregate itself does only a calculation. The normal approach is:

SELECT *
FROM yourQuery
WHERE dateColumn = ( 
    SELECT MAX(dateColumn) 
    FROM yourQuery
);

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Depending on the problem, the subquery must be correlated.
Jason PalmerAuthor Commented:
All sorted, thank you
johnsoneSenior Oracle DBACommented:
You don't need the subquery to get the max.  You can avoid hitting the table twice like that by using windowed aggregates.

A simple example would be:
SELECT doc_num, 
       modified_date 
FROM   ( 
                SELECT   doc_num, 
                         modified_date, 
                         row_number() over (paratition BY doc_num ORDER BY modified_date DESC) rn
                FROM     you_tab) 
WHERE  rn = 1;

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ste5anSenior DeveloperCommented:
Caveat: Test always both approaches. Cause ROW_NUMBER() is not necessarily always better.
johnsoneSenior Oracle DBACommented:
In most, but definitely not all, cases ROW_NUMBER will perform better as it only has to hit the base table once.

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Jason PalmerAuthor Commented:
Achieve the outcome i needed as shown below

select distinct doc_pfx, doc_num, AWB_BKD_WGT, AWB_BKD_VOL,PART_SHPMT_IND,
FLT_BKD_WGT, FLT_BKD_VOL,
ACCEPTED_WGT, ACCEPTED_VOL,

WGT_VAR, VOL_VAR
modified_date

from 

(Select  
--c.car_id,
b.doc_prfx as DOC_PFX, b.doc_num, 

a.bkd_wt as FLT_BKD_WGT, a.bkd_vol as FLT_BKD_VOL,
f.wt_bfr_awb as AWB_BKD_WGT, f.vol_bfr_awb as AWB_BKD_VOL,
a.part_shpmnt_ind as PART_SHPMT_IND,

g.num_pcs as ACCEPTED_PCS,
g.ttl_wt as ACCEPTED_WGT, g.vol as ACCEPTED_VOL,
g.ttl_wt - f.wt_bfr_awb as WGT_VAR,
g.vol - f.vol_bfr_awb  as VOL_VAR,


MAX(to_char(f.modified_date,  'DD-MON-YYYY HH24:MI:SS')) as modified_date

from sbh_res_itnry a, sbh_car b, sbh_res c, sbh_res_cust d, sbh_res f, sbh_AWB g
where c.car_id = b.car_id (+)
and c.car_id = a.car_id 
and c.car_id = d.car_id

and c.car_id = f.car_id 
and c.car_id = g.car_id
and a.aln_code = 'VS'
and a.flt_num = '0003'
and trunc (a.dep_date) = '04-APR-2017'
AND a.cncl_ind = 'N'
and d.cust_typ = 'AGT'
and b.cncl_ind = 'N'
--and c.enq_ind = 'N'
--and f.wt_bfr_awb is not null
--and b.doc_prfx = '932'
--and b.doc_num in ('51493422','51669634')

group by 
b.doc_prfx, b.doc_num, 
f.wt_bfr_awb, f.vol_bfr_awb,
g.num_pcs,
g.ttl_wt, g.vol,a.part_shpmnt_ind,
a.bkd_wt, a.bkd_vol 
)

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Jason PalmerAuthor Commented:
thanks for you help guys
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Query Syntax

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