Ontvang de enige laatste gegevens van vorige week en tel een kolom op

Ik denk dat dit overeenkomt met je verwachte resultaat:

select "user", "contact", "barcode", "date", "in", "out","dif"
     , sum("in"-"out") over(partition by "user", "contact") as "sum"
from (
    select "user", "contact", "barcode", "date", "in", "out","dif"
    , lag(dif,1) over(partition by "user", "contact" order by "date" ASC) prevdif
    , row_number() over(partition by "user", "contact" order by "date" DESC) rn
    from "table1" 
    where date_trunc('day', "date") <= '2017-06-25' ::date - (  interval '1 week')::interval 
    and "date" >  '2017-06-25'::date - (  interval '2 weeks')::interval 
    ) d
where rn in (1,2) and prevdif is not null
order by 1,2,4 DESC

Resultaat:

+----+-------+----------------+---------+---------------------+-----+-----+-----+-----+
|    | user  |    contact     | barcode |        date         | in  | out | dif | sum |
+----+-------+----------------+---------+---------------------+-----+-----+-----+-----+
|  1 | USER2 | Guillermo Tole |  987654 | 16.06.2017 05:27:00 | 500 | 420 |  80 | 170 |
|  2 | USER2 | Guillermo Tole |  281460 | 15.06.2017 05:36:00 | 310 | 220 |  90 | 170 |
|  3 | USER3 | Juan Rulfo     |  123456 | 15.06.2017 05:37:00 | 450 | 300 | 150 | 150 |
|  4 | USER3 | Pepito Marquez |  346234 | 15.06.2017 05:37:00 | 600 | 360 | 240 | 240 |
+----+-------+----------------+---------+---------------------+-----+-----+-----+-----+

Zie:http://rextester.com/ISHS42170

Voor voorwaarden zoals "meest recente" vind ik dat het gebruik van ROW_NUMBER() OVER() het handigst is, omdat hiermee de hele rij van elke "meest recente" gebeurtenis kan worden geretourneerd, wat niet zo eenvoudig is als MAX() en GROEP OP. "Afzonderlijke" resultaten worden geretourneerd door de rijen met waarde 1 te filteren die door de functie worden geretourneerd.

+BEWERK

In plaats van where rn in (1,2) te gebruiken Ik geloof dat een betere manier zou zijn geweest om barcode te gebruiken in de OVER(PARTITION BY...) voorwaarden, zoals deze:

select "user", "contact", "barcode", "date", "in", "out","dif"
     , sum("in"-"out") over(partition by "user", "contact") as "sum"
from (
    select "user", "contact", "barcode", "date", "in", "out","dif"
    , lag(dif,1) over(partition by "user", "contact", "barcode" order by "date" ASC) prevdif
    , row_number() over(partition by "user", "contact", "barcode" order by "date" DESC) rn
    from "table1" 
    where date_trunc('day', "date") <= '2017-06-25' ::date - (  interval '1 week')::interval 
    and "date" >  '2017-06-25'::date - (  interval '2 weeks')::interval 
    ) d
where rn = 1 and prevdif is not null
order by 1,2,4 DESC

http://rextester.com/SCV98254