count :SQL :DB2

Question

I have this table:

CODE	IDNR	NAME	LIMIT
123	80	XXX	2019-05
123	81	XXX	2019-10
124	80	YYY	2019-01
125	80	ZZZ	2019-05
125	81	ZZZ	2019-06
125	80	ZZZ	2019-07
126	80	III	2019-05
126	80	III	2019-09
126	80	III	2019-07

I want to have a new column (Count-LIMIT ) contain how many LIMIT per code, and another contain YES if the limit are continuous and No if not. MY RESULT that I want like:

CODE	IDNR	NAME	LIMIT	Count-Limit	CON
123	80	XXX	2019-05	2	NO
123	81	XXX	2019-10	2	NO
124	80	YYY	2019-01	1	NO
125	80	ZZZ	2019-05	3	YES
125	81	ZZZ	2019-06	3	YES
125	80	ZZZ	2019-07	3	YES
126	80	III	2019-05	3	NO
126	80	III	2019-09	3	NO
126	80	III	2019-07	3	NO

THANKS!

Answer 1

Try this:

WITH T (CODE, IDNR, NAME, LIMIT) AS
(
VALUES
  (123, 80, 'XXX', '2019-05')
, (123, 81, 'XXX', '2019-10')
, (124, 80, 'YYY', '2019-01')
, (125, 80, 'ZZZ', '2019-05')
, (125, 81, 'ZZZ', '2019-06')
, (125, 80, 'ZZZ', '2019-07')
, (126, 80, 'III', '2019-05')
, (126, 80, 'III', '2019-09')
, (126, 80, 'III', '2019-07')
)
SELECT 
  T.*
, COUNT (1) OVER (PARTITION BY CODE) AS COUNT_LIMIT
, DECODE
(
  TO_DATE (LIMIT || '-01', 'YYYY-MM-DD') 
, COALESCE
  (
    LAG  (TO_DATE (LIMIT || '-01', 'YYYY-MM-DD')) OVER (PARTITION BY CODE ORDER BY LIMIT) + 1 MONTH
  , LEAD (TO_DATE (LIMIT || '-01', 'YYYY-MM-DD')) OVER (PARTITION BY CODE ORDER BY LIMIT) - 1 MONTH
  )
, 'YES', 'NO'
) AS CON
FROM T
ORDER BY CODE, LIMIT

The result is:

CODE	IDNR	NAME	LIMIT	COUNT_LIMIT	CON
123	80	XXX	2019-05	2	NO
123	81	XXX	2019-10	2	NO
124	80	YYY	2019-01	1	NO
125	80	ZZZ	2019-05	3	YES
125	81	ZZZ	2019-06	3	YES
125	80	ZZZ	2019-07	3	YES
126	80	III	2019-05	3	NO
126	80	III	2019-07	3	NO
126	80	III	2019-09	3	NO