SQL - values from two rows into new two rows - sql

Question

I have a query that gives a sum of quantity of items on working days. on weekend and holidays that quantity value and item value is empty.
I would like that on empty days is last known quantity and item.
My query is like this:
`select a.dt,b.zaliha as quantity,b.artikal as item
from
(select to_date('01-01-2017', 'DD-MM-YYYY') + rownum -1 dt
from dual
connect by level <= to_date(sysdate) - to_date('01-01-2017', 'DD-MM-YYYY') + 1
order by 1)a
LEFT OUTER JOIN
(select kolicina,sum(kolicina)over(partition by artikal order by datum_do) as zaliha,datum_do,artikal
from
(select sum(vv.kolicinaulaz-vv.kolicinaizlaz)kolicina,vz.datum as datum_do,vv.artikal
from vlpzaglavlja vz, vlpvarijante vv
where vz.id=vv.vlpzaglavlje
and vz.orgjed='01006'
and vv.skladiste='01006'
and vv.artikal in (3069,6402)
group by vz.datum,vv.artikal
order by vv.artikal,vz.datum asc)
order by artikal,datum_do asc)b
on a.dt=b.datum_do
where a.dt between to_date('12102017','ddmmyyyy') and to_date('16102017','ddmmyyyy')
order by a.dt`
and my output is like this:
and I want this:

Answer 1

In short, if quantity is null use lag(... ignore nulls) and coalesce or nvl:
select dt, item,
nvl(quantity, lag(quantity ignore nulls) over (partition by item order by dt))
from t
order by dt, item
Here is the full query, I cannot test it, but it is something like:
with t as (
select a.dt, b.zaliha as quantity, b.artikal as item
from (
select date '2017-10-10' + rownum - 1 dt
from dual
connect by date '2017-10-10' + rownum - 1 <= date '2017-10-16' ) a
left join (
select kolicina, datum_do, artikal,
sum(kolicina) over(partition by artikal order by datum_do) as zaliha
from (
select sum(vv.kolicinaulaz-vv.kolicinaizlaz) kolicina,
vz.datum as datum_do, vv.artikal
from vlpzaglavlja vz
join vlpvarijante vv on vz.id = vv.vlpzaglavlje
where vz.orgjed = '01006' and vv.skladiste='01006'
and vv.artikal in (3069,6402)
group by vz.datum, vv.artikal)) b
on a.dt = b.datum_do)
select *
from (
select dt, item,
nvl(quantity, lag(quantity ignore nulls)
over (partition by item order by dt)) qty
from t)
where dt >= date '2017-10-12'
order by dt, item
There are several issues in your query, major and minor:
in date generator (subquery a) you are selecting dates from long period, january to september, then joining with main tables and summing data and then selecting only small part. Why not filter dates at first?,
to_date(sysdate). sysdate is already date,
use ansi joins,
do not use order by in subqueries, it has no impact, only last ordering is important,
use date literals when defining dates, it is more readable.