寻找一种方法来将多行休假请求合并到基于请求的休假日期的一行中

Question

I'm attempting to consolidate some Time off requests from multiple rows into one row which identifies the start and end time. The current table looks similar to the following;

ID	hours per day	Submitted Date	Requested Date	Requested Status
'Joe'	8	'2017-12-01'	'2017-12-05'	'Approved'
'Joe'	8	'2017-12-01'	'2017-12-06'	'Approved'
'Joe'	4	'2017-12-01'	'2017-12-07'	'Declined'
'suzie'	8	'2018-09-08'	'2017-12-24'	'Approved'
'suzie'	8	'2018-09-08'	'2017-12-25'	'Approved'
'Joe'	2	'2017-12-01'	'2017-12-7'	'Approved'

I'm trying to condense this into the following:

ID	Total Hours	Submitted Date	Requested Date Start	Requested Date End	Requested Status
Joe	16	'2017-12-01'	'2017-12-05'	'2017-12-06'	Approved
Joe	4	'2017-12-01'	'2017-12-07'	'2017-12-07'	Declined
suzie	16	'2018-09-08'	'2017-12-24'	'2017-12-25'	Approved
Joe	2	'2017-12-01'	'2017-12-07'	'2017-12-07'	Approved

I've tried dozens of things utilizing partitions but i'm not really getting anywhere. Any suggestions?

Answer 1

This is a gaps and islands problem. Assuming you are using MySQL 8+ we can use the difference in row numbers method here:

WITH cte AS (
    SELECT *, ROW_NUMBER() OVER (PARTITION BY ID ORDER BY RequestedDate) rn1,
              ROW_NUMBER() OVER (PARTITION BY ID, RequestedStatus
                                 ORDER BY RequestedDate) rn2
    FROM yourTable
)

SELECT ID, SUM(hoursperday) AS total_hours, SubmittedDate,
       MIN(RequestedDate) AS rd_start, MAX(RequestedDate) AS rd_end,
       RequestedStatus
FROM cte
GROUP BY ID, SubmittedDate, RequestedStatus, rn1 - rn2
ORDER BY ID, RequestedStatus, MIN(RequestedDate);

Demo