从表中复制并提取以前的记录

Question

I have transactions and reservations table. I have to join and fetch checkin and checkout data from reservations. But one issue I have is if there is a change only in the reservations, i have to copy the transactions to a new row and change fiscal period to changeDate and add new checkin-checkout date.

Reservations:

I tried with the query but not sure how to pick up the records from other table from previous rows:

SELECT  IFNULL(a."fiscalPeriod","changeDate") as "fiscalPeriod"
        ,b."purchaseId","charge","refund","checkIn","checkOut" 
 FROM  reservations a 
         FULL OUTER JOIN transactions b
 ON a."purchaseId"=b."purchaseId"  
   and b."fiscalPeriod" >= "validfrom"
   and b."fiscalPeriod"  < "validTo"  
 

Output:

Answer 1

You could use FIRST_VALUE analytic function with windowing clause considereing just 1 previous and current row. There were some other issues in your SQL. Anyway here is the code with the result. The WITH clause is here just to generate sample data and, as such, it is not a part of the answer

WITH
    transactions AS
        (
            Select 2022002 "FISC_PERIOD", 'P1' "PURCHASE_ID", 100 "CHARGE", 50 "REFUND" From Dual 
        ),
    reservations AS
        (
            Select 'P1' "PURCHASE_ID", 2022001 "VALID_FROM", 2022003 "VALID_TO", 2022004 "CHECK_IN", 2022005 "CHECK_OUT", 2022001 "CHANGE_DATE" From Dual Union All
            Select 'P1' "PURCHASE_ID", 2022003 "VALID_FROM", 9999012 "VALID_TO", 2022011 "CHECK_IN", 2022012 "CHECK_OUT", 2022003 "CHANGE_DATE" From Dual
        )
SELECT  
    Nvl(a.FISC_PERIOD, b.CHANGE_DATE) "FISC_PERIOD", 
    b.PURCHASE_ID "PURCHASE_ID", 
    Nvl(a.CHARGE, FIRST_VALUE(a.CHARGE) OVER(PARTITION BY b.PURCHASE_ID ORDER BY b.PURCHASE_ID, b.VALID_FROM ROWS BETWEEN 1 PRECEDING AND CURRENT ROW)) "CHARGE", 
    Nvl(a.REFUND, FIRST_VALUE(a.REFUND) OVER(PARTITION BY b.PURCHASE_ID ORDER BY b.PURCHASE_ID, b.VALID_FROM ROWS BETWEEN 1 PRECEDING AND CURRENT ROW)) "REFUND", 
    b.CHECK_IN "CHECK_IN", 
    b.CHECK_OUT  "CHECK_OUT"
FROM  reservations b 
LEFT JOIN  transactions a
        ON (a.PURCHASE_ID = b.PURCHASE_ID and 
            a.FISC_PERIOD >= b.VALID_FROM and 
            a.FISC_PERIOD  < b.VALID_TO)
--  
--  R e s u l t
--
--  FISC_PERIOD PURCHASE_ID     CHARGE     REFUND   CHECK_IN  CHECK_OUT
--  ----------- ----------- ---------- ---------- ---------- ----------
--     2022002 P1                 100         50    2022004    2022005 
--     2022003 P1                 100         50    2022011    2022012

Here is reservations table in the FROM clause and LEFT JOIN to transactons on the same conditions. When selecting data from transactions (CHARGE, REFUND) if value is null there is a FIRST_VALUE analytic function (considering just 1 previous and current row) to get you the value from the preceding row. Regards...