Need help in query..for a select / update on multiple rows

Question

DROP TABLE TEST;
CREATE TABLE TEST (ACCOUNT_NUMBER VARCHAR2(30), TIER_NUMBER NUMBER, FROM_DATE DATE, TO_DATE DATE)
INSERT INTO TEST(ACCOUNT_NUMBER, TIER_NUMBER, FROM_DATE, TO_DATE) VALUES ('11111', 1, '28-FEB-11','28-FEB-11');
INSERT INTO TEST(ACCOUNT_NUMBER, TIER_NUMBER, FROM_DATE, TO_DATE) VALUES ('11111', 2, '28-FEB-11','28-FEB-11');
INSERT INTO TEST(ACCOUNT_NUMBER, TIER_NUMBER, FROM_DATE, TO_DATE) VALUES ('11111', 3, '28-FEB-11','01-MAR-11');
INSERT INTO TEST(ACCOUNT_NUMBER, TIER_NUMBER, FROM_DATE, TO_DATE) VALUES ('11111', 1, '01-MAR-11','01-MAR-11');
INSERT INTO TEST(ACCOUNT_NUMBER, TIER_NUMBER, FROM_DATE, TO_DATE) VALUES ('11111', 2, '01-MAR-11','01-MAR-11');
INSERT INTO TEST(ACCOUNT_NUMBER, TIER_NUMBER, FROM_DATE, TO_DATE) VALUES ('11111', 1, '02-MAR-11',NULL);
INSERT INTO TEST(ACCOUNT_NUMBER, TIER_NUMBER, FROM_DATE, TO_DATE) VALUES ('11111', 2, '02-MAR-11',NULL);
INSERT INTO TEST(ACCOUNT_NUMBER, TIER_NUMBER, FROM_DATE, TO_DATE) VALUES ('11111', 3, '02-MAR-11',NULL);
in this table, for each FROM_DATE, the TO_DATE value should be same for all tiers.
In the above data, for FROM_DATE = 28-Feb-11, there are 3 rows with TIER_NUMBER = 1, 2, 3.
TIER_NUMBER = 1,2 --> TO_DATE = 28-FEB-11
But for TIER_NUMBER = 3 --> TO_DATE = 01-MAR-11 (this occurred due to some incorrect logic).
Any help on how to identify such records with wrong data?
And how to update the TIER_NUMBER=3 row with TO_DATE = 28-FEB-11 (whatever we have in TO_DATE for TIER_NUMBER = 1 as that is the minimum tier)?
The table would contain millions of accounts and atleast 6 rows for each account.
Thanks.

Answer 1

Hi,
I think this should solve your problem
Declare
todate date;
differenc number;
      CURSOR myCursor IS
       select to_date, FIRST_VALUE(TO_DATE) over
(partition by account_number, from_date order by tier_number) - to_date as differ from test
        FOR UPDATE of to_date;
   BEGIN
     FOR idx IN myCursor LOOP
       todate :=idx.to_date;
        differenc := idx.differ;
        UPDATE test
        SET to_date = todate + differenc
      WHERE CURRENT OF myCursor;
     END LOOP;
     COMMIT;
   END;
   /It both finds and updates rows that doesn't have correct to_date value