Determining consecutive and independent PTO days - sql

Question

Based on feedback, I am restructuring my question.
I am working with SQL on a Presto database.
My objective is to report on employees that take consecutive days of PTO or Sick Time since the beginning of 2018. My desired output would have the individual islands of time taken by employee with the start and end dates, along the lines of:
The main table I am using is d_employee_time_off
There are only two time_off_type_name: PTO and Sick Leave.
The ds is a datestamp and I use the latest ds (usually the current date)
I have access to a date table named d_date
I can join the tables on d_employee_time_off.time_off_date = d_date.full_date
I hope that I have structured this question in a fashion that is understandable.

Answer 1

I believe the need here is to join the day off material to a calendar table.
In the example solution below I am generating this "on the fly" but I think you do have your own solution for this. Also in my example I have used the string 'Monday' and moved backward from that (or, you could use 'Friday' and move forward). I'm, not keen on language dependent solutions but as I'm not a Presto user wasn't able to test anything on Presto. So the example below uses some of your own logic, but using SQL Server syntax which I trust you can translate to Presto:
Query:
;WITH
Digits AS (
SELECT 0 AS digit UNION ALL
SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL
SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL
SELECT 9
)
, cal AS (
SELECT
ca.number
, dateadd(day,ca.number,'20180101') as cal_date
, datename(weekday,dateadd(day,ca.number,'20180101')) weekday
FROM Digits [1s]
CROSS JOIN Digits [10s]
CROSS JOIN Digits [100s] /* add more like this as needed */
cross apply (
SELECT
[1s].digit
+ [10s].digit * 10
+ [100s].digit * 100 /* add more like this as needed */
AS number
) ca
)
, time_off AS (
select
*
from cal
inner join mytable t on (cal.cal_date = t.time_off_date and cal.weekday <> 'Monday')
or (cal.cal_date between dateadd(day,-2,t.time_off_date)
and t.time_off_date and datename(weekday,t.time_off_date) = 'Monday')
)
, starting_points AS (
SELECT
employee_id,
cal_date,
dense_rank() OVER(partition by employee_id
ORDER BY
time_off_date
) AS rownum
FROM
time_off A
WHERE
NOT EXISTS (
SELECT
*
FROM
time_off B
WHERE
B.employee_id = A.employee_id
AND B.cal_date = DATEADD(day, -1, A.cal_date)
)
)
, ending_points AS (
SELECT
employee_id,
cal_date,
dense_rank() OVER(partition by employee_id
ORDER BY
time_off_date
) AS rownum
FROM
time_off A
WHERE
NOT EXISTS (
SELECT
*
FROM
time_off B
WHERE
B.employee_id = A.employee_id
AND B.cal_date = DATEADD(day, 1, A.cal_date)
)
)
SELECT
S.employee_id,
S.cal_date AS start_range,
E.cal_date AS end_range
FROM
starting_points S
JOIN
ending_points E
ON E.employee_id = S.employee_id
AND E.rownum = S.rownum
order by employee_id
, start_range
Result:
employee_id start_range end_range
1 200035 02.01.2018 02.01.2018
2 200035 20.04.2018 27.04.2018
3 200037 27.01.2018 29.01.2018
4 200037 31.03.2018 02.04.2018
see: http://rextester.com/MISZ50793
CREATE TABLE mytable(
ID INT NOT NULL
,employee_id INTEGER NOT NULL
,type VARCHAR(3) NOT NULL
,time_off_date DATE NOT NULL
,time_off_in_days INT NOT NULL
);
INSERT INTO mytable(id,employee_id,type,time_off_date,time_off_in_days) VALUES (1,200035,'PTO','2018-01-02',1);
INSERT INTO mytable(id,employee_id,type,time_off_date,time_off_in_days) VALUES (2,200035,'PTO','2018-04-20',1);
INSERT INTO mytable(id,employee_id,type,time_off_date,time_off_in_days) VALUES (3,200035,'PTO','2018-04-23',1);
INSERT INTO mytable(id,employee_id,type,time_off_date,time_off_in_days) VALUES (4,200035,'PTO','2018-04-24',1);
INSERT INTO mytable(id,employee_id,type,time_off_date,time_off_in_days) VALUES (5,200035,'PTO','2018-04-25',1);
INSERT INTO mytable(id,employee_id,type,time_off_date,time_off_in_days) VALUES (6,200035,'PTO','2018-04-26',1);
INSERT INTO mytable(id,employee_id,type,time_off_date,time_off_in_days) VALUES (7,200035,'PTO','2018-04-27',1);
INSERT INTO mytable(id,employee_id,type,time_off_date,time_off_in_days) VALUES (8,200037,'PTO','2018-01-29',1);
INSERT INTO mytable(id,employee_id,type,time_off_date,time_off_in_days) VALUES (9,200037,'PTO','2018-04-02',1);