Q: How can I rank records based on 1 column's changing value?
I have the following data (https://pastebin.com/vdTb1JRT):
EmployeeID Date Onleave
ABH12345 2016-01-01 0
ABH12345 2016-01-02 0
ABH12345 2016-01-03 0
ABH12345 2016-01-04 0
ABH12345 2016-01-05 0
ABH12345 2016-01-06 0
ABH12345 2016-01-07 0
ABH12345 2016-01-08 0
ABH12345 2016-01-09 0
ABH12345 2016-01-10 1
ABH12345 2016-01-11 1
ABH12345 2016-01-12 1
ABH12345 2016-01-13 1
ABH12345 2016-01-14 0
ABH12345 2016-01-15 0
ABH12345 2016-01-16 0
ABH12345 2016-01-17 0
I would like to produce the following results:
EmployeeID DateValidFrom DateValidTo OnLeave
ABH12345 2016-01-01 2016-01-09 0
ABH12345 2016-01-10 2016-01-13 1
ABH12345 2016-01-14 2016-01-17 0
So I'm thinking if I can somehow create a ranked column (like shown below) that increments based on the value in the Onleave column - partitioned by the EmployeeID column.
EmployeeID Date Onleave RankedCol
ABH12345 2016-01-01 0 1
ABH12345 2016-01-02 0 1
ABH12345 2016-01-03 0 1
ABH12345 2016-01-04 0 1
ABH12345 2016-01-05 0 1
ABH12345 2016-01-06 0 1
ABH12345 2016-01-07 0 1
ABH12345 2016-01-08 0 1
ABH12345 2016-01-09 0 1
ABH12345 2016-01-10 1 2
ABH12345 2016-01-11 1 2
ABH12345 2016-01-12 1 2
ABH12345 2016-01-13 1 2
ABH12345 2016-01-14 0 3
ABH12345 2016-01-15 0 3
ABH12345 2016-01-16 0 3
ABH12345 2016-01-17 0 3
Then I would be able to do the following:
SELECT
[EmployeeID] = [EmployeeID]
,[DateValidFrom] = MIN([Date])
,[DateValidTo] = MAX([Date])
,[OnLeave] = [OnLeave]
FROM table/view/cte/sub-query
GROUP BY
[EmployeeID]
,[OnLeave]
,[RankedCol]
Other solutions are very welcome..
Below is the test data :
WITH CTE AS ( SELECT EmployeeID = 'ABH12345', [Date] = CAST(N'2016-01-01' AS Date), [Onleave] = 0
UNION SELECT 'ABH12345', CAST(N'2016-01-02' AS Date), 0
UNION SELECT 'ABH12345', CAST(N'2016-01-03' AS Date), 0
UNION SELECT 'ABH12345', CAST(N'2016-01-04' AS Date), 0
UNION SELECT 'ABH12345', CAST(N'2016-01-05' AS Date), 0
UNION SELECT 'ABH12345', CAST(N'2016-01-06' AS Date), 0
UNION SELECT 'ABH12345', CAST(N'2016-01-07' AS Date), 0
UNION SELECT 'ABH12345', CAST(N'2016-01-08' AS Date), 0
UNION SELECT 'ABH12345', CAST(N'2016-01-09' AS Date), 0
UNION SELECT 'ABH12345', CAST(N'2016-01-10' AS Date), 1
UNION SELECT 'ABH12345', CAST(N'2016-01-11' AS Date), 1
UNION SELECT 'ABH12345', CAST(N'2016-01-12' AS Date), 1
UNION SELECT 'ABH12345', CAST(N'2016-01-13' AS Date), 1
UNION SELECT 'ABH12345', CAST(N'2016-01-14' AS Date), 0
UNION SELECT 'ABH12345', CAST(N'2016-01-15' AS Date), 0
UNION SELECT 'ABH12345', CAST(N'2016-01-16' AS Date), 0
UNION SELECT 'ABH12345', CAST(N'2016-01-17' AS Date), 0
)
SELECT * FROM CTE