Identify contiguous and discontinuous date ranges - sql

Question

I have a table named x . The data is as follows.
Acccount_num start_dt end_dt
A111326 02/01/2016 02/11/2016
A111326 02/12/2016 03/05/2016
A111326 03/02/2016 03/16/2016
A111331 02/28/2016 02/29/2016
A111331 02/29/2016 03/29/2016
A999999 08/25/2015 08/25/2015
A999999 12/19/2015 12/22/2015
A222222 11/06/2015 11/10/2015
A222222 05/16/2016 05/17/2016
Both A111326 and A111331 should be identified as contiguous data and A999999 and
A222222 should be identified as discontinuous data.In my code I currently use the following query to identify discontinuous data. The A111326 is also erroneously identified as discontinuous data. Please help to modify the below code so that A111326 is not identified as discontinuous data.Thanks in advance for your help.
(SELECT account_num
FROM (SELECT account_num,
(MAX (
END_DT)
OVER (PARTITION BY account_num
ORDER BY START_DT))
START_DT,
(LEAD (
START_DT)
OVER (PARTITION BY account_num
ORDER BY START_DT))
END_DT
FROM x
WHERE (START_DT + 1) <=
(END_DT - 1))
WHERE START_DT < END_DT);

Answer 1

Oracle Setup:
CREATE TABLE accounts ( Account_num, start_dt, end_dt ) AS
SELECT 'A', DATE '2016-02-01', DATE '2016-02-11' FROM DUAL UNION ALL
SELECT 'A', DATE '2016-02-12', DATE '2016-03-05' FROM DUAL UNION ALL
SELECT 'A', DATE '2016-03-02', DATE '2016-03-16' FROM DUAL UNION ALL
SELECT 'B', DATE '2016-02-28', DATE '2016-02-29' FROM DUAL UNION ALL
SELECT 'B', DATE '2016-02-29', DATE '2016-03-29' FROM DUAL UNION ALL
SELECT 'C', DATE '2015-08-25', DATE '2015-08-25' FROM DUAL UNION ALL
SELECT 'C', DATE '2015-12-19', DATE '2015-12-22' FROM DUAL UNION ALL
SELECT 'D', DATE '2015-11-06', DATE '2015-11-10' FROM DUAL UNION ALL
SELECT 'D', DATE '2016-05-16', DATE '2016-05-17' FROM DUAL UNION ALL
SELECT 'E', DATE '2016-01-01', DATE '2016-01-02' FROM DUAL UNION ALL
SELECT 'E', DATE '2016-01-05', DATE '2016-01-06' FROM DUAL UNION ALL
SELECT 'E', DATE '2016-01-03', DATE '2016-01-07' FROM DUAL;
Query:
WITH times ( account_num, dt, lvl ) AS (
SELECT Account_num, start_dt - 1, 1 FROM accounts
UNION ALL
SELECT Account_num, end_dt, -1 FROM accounts
)
, totals ( account_num, dt, total ) AS (
SELECT account_num,
dt,
SUM( lvl ) OVER ( PARTITION BY Account_num ORDER BY dt, lvl DESC )
FROM times
)
SELECT Account_num,
CASE WHEN COUNT( CASE total WHEN 0 THEN 1 END ) > 1
THEN 'N'
ELSE 'Y'
END AS is_contiguous
FROM totals
GROUP BY Account_Num
ORDER BY Account_Num;
Output:
ACCOUNT_NUM IS_CONTIGUOUS
----------- -------------
A Y
B Y
C N
D N
E Y
Alternative Query:
(It's exactly the same method just using UNPIVOT rather than UNION ALL.)
SELECT Account_num,
CASE WHEN COUNT( CASE total WHEN 0 THEN 1 END ) > 1
THEN 'N'
ELSE 'Y'
END AS is_contiguous
FROM (
SELECT Account_num,
SUM( lvl ) OVER ( PARTITION BY Account_Num
ORDER BY CASE lvl WHEN 1 THEN dt - 1 ELSE dt END,
lvl DESC
) AS total
FROM accounts
UNPIVOT ( dt FOR lvl IN ( start_dt AS 1, end_dt AS -1 ) )
)
GROUP BY Account_Num
ORDER BY Account_Num;

Answer 2

WITH cte AS (
SELECT
AccountNumber
,CASE
WHEN
LAG(End_Dt) OVER (PARTITION BY AccountNumber ORDER BY End_Dt) IS NULL THEN 0
WHEN
LAG(End_Dt) OVER (PARTITION BY AccountNumber ORDER BY End_Dt) >= Start_Dt - 1 THEN 0
ELSE 1
END as discontiguous
FROM
#Table
)
SELECT
AccountNumber
,CASE WHEN SUM(discontiguous) > 0 THEN 'discontiguous' ELSE 'contiguous' END
FROM
cte
GROUP BY
AccountNumber;
One of your problems is that your contiguous desired result also includes overlapping date ranges in your example data set. Example A111326 Starts on 3/2/2016 but ends the row before on 3/5/2015 meaning it overlaps by 3 days.