Oracle Sort of gaps and island query - sql

Question

Instead of writing long sentences and paragraphs let me show the data and what I want to achieve :
create table ssb_price (itm_no varchar2(10), price number, price_code varchar2(10), valid_from_dt date, valid_to_dt date);
insert into ssb_price values ('A001', 83, 'AB', '01-JAN-21', '05-JAN-21');
insert into ssb_price values ('A001', 83, 'AB', '06-JAN-21', '12-JAN-21');
insert into ssb_price values ('A001', 98, 'SPQ', '13-JAN-21', '17-JAN-21');
insert into ssb_price values ('A001', 83, 'AB', '19-JAN-21', '24-JAN-21');
insert into ssb_price values ('A001', 83, 'DE', '25-JAN-21', '30-JAN-21');
insert into ssb_price values ('A001', 83, 'DE', '31-JAN-21', '04-FEB-21');
insert into ssb_price values ('A001', 77, 'XY', '07-FEB-21', '12-FEB-21');
insert into ssb_price values ('A001', 77, 'XY', '15-FEB-21', '20-FEB-21');
insert into ssb_price values ('A001', 62, 'SD', '23-FEB-21', '26-FEB-21');
insert into ssb_price values ('A001', 59, 'SD', '26-FEB-21', '03-MAR-21');
For particular itm_no and price if the from and to dates are continuous then I should get that value. For price 77 there is a gap of 2 days (13th and 14th) between to date and the next from date so its not continuous. Lemme paste what the desired output should look like :(taken the snip from excel)
I have asked this question clubbed with another post. But that post was old and haven't got any feedback so creating this. Please let me know if I should merge this post with the previous one.

Answer 1

This is basically a gaps-and-islands problem. But instead of aggregating to reduce the number of rows, you want to use window functions at the last step.
In your data, the time frames neatly tile. That suggests using lag() and a cumulative sum to define the groups:
select p.*,
min(valid_from_dt) over (partition by itm_no, price, price_code, grp) as new_valid_from_dt,
max(valid_to_dt) over (partition by itm_no, price, price_code, grp) as new_valid_to_dt
from (select p.*,
sum(case when valid_from_dt = prev_valid_to_dt + interval '1' day then 0 else 1 end) over
(partition by itm_no, price, price_code order by valid_from_dt) as grp
from (select p.*,
lag(valid_to_dt) over (partition by itm_no, price, price_code order by valid_from_dt) as prev_valid_to_dt
from ssb_price p
) p
) p
order by itm_no, valid_from_dt;
Here is a db<>fiddle.

Answer 2

From Oracle 12, you can use MATCH_RECOGNIZE:
SELECT itm_no,
price,
price_code,
valid_from_dt,
valid_to_dt,
MIN( valid_from_dt ) OVER ( PARTITION BY itm_no, mnum ) AS new_valid_from_dt,
MAX( valid_to_dt ) OVER ( PARTITION BY itm_no, mnum ) AS new_valid_to_dt
FROM ssb_price
MATCH_RECOGNIZE(
PARTITION BY itm_no
ORDER BY valid_from_dt, valid_to_dt
MEASURES
MATCH_NUMBER() AS mnum
ALL ROWS PER MATCH
PATTERN ( start_range continued_range* )
DEFINE
continued_range AS (
valid_from_dt = PREV( valid_to_dt ) + 1
AND price = PREV( price )
)
)
and, from Oracle 10g, you can use the MODEL clause:
SELECT itm_no,
price,
price_code,
valid_from_dt,
valid_to_dt,
mn,
MIN( valid_from_dt ) OVER ( PARTITION BY itm_no, mn ) AS new_valid_from_dt,
MAX( valid_to_dt ) OVER ( PARTITION BY itm_no, mn ) AS new_valid_to_dt
FROM (
SELECT *
FROM (
SELECT s.*,
ROW_NUMBER() OVER ( PARTITION BY itm_no ORDER BY valid_from_dt ) AS rn
FROM ssb_price s
)
MODEL
PARTITION BY ( itm_no )
DIMENSION BY ( rn )
MEASURES ( price, price_code, valid_from_dt, valid_to_dt, 1 AS mn )
RULES (
mn[rn>1] = mn[cv(rn)-1]
+
CASE
WHEN valid_from_dt[cv(rn)] = valid_to_dt[cv(rn)-1] + 1
AND price[cv(rn)] = price[cv(rn) - 1]
THEN 0
ELSE 1
END
)
)
Which, for the sample data:
create table ssb_price (itm_no, price, price_code, valid_from_dt, valid_to_dt) AS
SELECT 'A001', 83, 'AB', DATE '2021-01-01', DATE '2021-01-05' FROM DUAL UNION ALL
SELECT 'A001', 83, 'AB', DATE '2021-01-06', DATE '2021-01-12' FROM DUAL UNION ALL
SELECT 'A001', 98, 'SPQ', DATE '2021-01-13', DATE '2021-01-17' FROM DUAL UNION ALL
SELECT 'A001', 83, 'AB', DATE '2021-01-19', DATE '2021-01-24' FROM DUAL UNION ALL
SELECT 'A001', 83, 'DE', DATE '2021-01-25', DATE '2021-01-30' FROM DUAL UNION ALL
SELECT 'A001', 83, 'DE', DATE '2021-01-31', DATE '2021-02-04' FROM DUAL UNION ALL
SELECT 'A001', 77, 'XY', DATE '2021-02-07', DATE '2021-02-12' FROM DUAL UNION ALL
SELECT 'A001', 77, 'XY', DATE '2021-02-15', DATE '2021-02-20' FROM DUAL UNION ALL
SELECT 'A001', 62, 'SD', DATE '2021-02-23', DATE '2021-02-26' FROM DUAL UNION ALL
SELECT 'A001', 59, 'SD', DATE '2021-02-26', DATE '2021-03-03' FROM DUAL;
Outputs:
ITM_NO
PRICE
PRICE_CODE
VALID_FROM_DT
VALID_TO_DT
NEW_VALID_FROM_DT
NEW_VALID_TO_DT
A001
83
AB
2021-01-01 00:00:00
2021-01-05 00:00:00
2021-01-01 00:00:00
2021-01-12 00:00:00
A001
83
AB
2021-01-06 00:00:00
2021-01-12 00:00:00
2021-01-01 00:00:00
2021-01-12 00:00:00
A001
98
SPQ
2021-01-13 00:00:00
2021-01-17 00:00:00
2021-01-13 00:00:00
2021-01-17 00:00:00
A001
83
AB
2021-01-19 00:00:00
2021-01-24 00:00:00
2021-01-19 00:00:00
2021-02-04 00:00:00
A001
83
DE
2021-01-25 00:00:00
2021-01-30 00:00:00
2021-01-19 00:00:00
2021-02-04 00:00:00
A001
83
DE
2021-01-31 00:00:00
2021-02-04 00:00:00
2021-01-19 00:00:00
2021-02-04 00:00:00
A001
77
XY
2021-02-07 00:00:00
2021-02-12 00:00:00
2021-02-07 00:00:00
2021-02-12 00:00:00
A001
77
XY
2021-02-15 00:00:00
2021-02-20 00:00:00
2021-02-15 00:00:00
2021-02-20 00:00:00
A001
62
SD
2021-02-23 00:00:00
2021-02-26 00:00:00
2021-02-23 00:00:00
2021-02-26 00:00:00
A001
59
SD
2021-02-26 00:00:00
2021-03-03 00:00:00
2021-02-26 00:00:00
2021-03-03 00:00:00
db<>fiddle here