Forkert næste dato fra en datokolonne for alle Oracle-kunder

Din vinduesklausul ser på last_effective_dates på tværs af alle dine data. Du skal tilføje en partition by klausul for at begrænse det til den nuværende kunde:

  OVER (PARTITION BY nm.CUSTOMER_ID
        ORDER BY nm.LATEST_EFFECTIVE_DATE
        RANGE BETWEEN 1 FOLLOWING AND UNBOUNDED FOLLOWING)

Så:

  SELECT NM.CUSTOMER_ID customer_id,
     NM.LATEST_EFFECTIVE_DATE start_date,
     NVL (
        CASE
           WHEN nm.LATEST_EFFECTIVE_DATE IS NULL
           THEN
              TO_DATE ('12/12/9999', 'dd/mm/yyyy')
           ELSE
              FIRST_VALUE (
                 nm.LATEST_EFFECTIVE_DATE)
              OVER (PARTITION BY nm.CUSTOMER_ID
                    ORDER BY nm.LATEST_EFFECTIVE_DATE
                    RANGE BETWEEN 1 FOLLOWING AND UNBOUNDED FOLLOWING)
        END,
        TO_DATE ('12/12/9999', 'dd/mm/yyyy'))
        end_date,
     NM.PRESENT_QUANTITY PRESENT_quantity
FROM nm_cust_appliance_history nm
WHERE NM.APPLIANCE_INFO_ID = 10484
ORDER BY customer_id, start_date;

Hvis du nogensinde har brug for at køre det for mere end én appliance_info_id så bliver du nødt til at tilføje det til partition by clause også.

Brug af en dummy-ekstra-record til på en måde at simulere det, du ser, leveret via en CTE:

with nm_cust_appliance_history(appliance_info_id, customer_id, latest_effective_date, present_quantity) as (
  select 10484, 96, date '2009-12-20', 10 from dual
  union all select 10484, 96, date '2014-11-18', 12 from dual
  union all select 10484, 96, date '2015-11-26', 14 from dual
  union all select 10484, 42, date '2009-12-21', 15 from dual
)

din oprindelige forespørgsel får:

CUSTOMER_ID START_DATE END_DATE   PRESENT_QUANTITY
----------- ---------- ---------- ----------------
         42 2009-12-21 2014-11-18               15
         96 2009-12-20 2009-12-21               10
         96 2014-11-18 2015-11-26               12
         96 2015-11-26 9999-12-12               14

og partition-by-forespørgslen ovenfor får:

CUSTOMER_ID START_DATE END_DATE   PRESENT_QUANTITY
----------- ---------- ---------- ----------------
         42 2009-12-21 9999-12-12               15
         96 2009-12-20 2014-11-18               10
         96 2014-11-18 2015-11-26               12
         96 2015-11-26 9999-12-12               14