How to group by ID as well as date with this query - sql

Question

This is a followup to a question I posted earlier. This code does exactly what I was asking about but I realized upon finally getting it working that what I was trying to do isn't actually quite what I need.
DECLARE #StartDateTime datetime = '2015-07-13 14:00:00',
#EndDateTime datetime = '2015-07-13 16:00:00';
WITH JumpsOf15 AS
(
SELECT ROW_NUMBER() OVER(ORDER BY object_id) * 15 AS Step
FROM sys.objects
),
Dates as
(
SELECT currentDate = steppedDate.steppedDate
FROM JumpsOf15
CROSS APPLY(SELECT DATEADD(MINUTE,Step,#StartDateTime) AS steppedDate ) AS steppedDate
WHERE #EndDateTime>steppedDate.steppedDate
)
SELECT d.currentDate, t.Value, t.FK_ConfigId
FROM Dates AS d
OUTER APPLY
( SELECT TOP 1 t.[Timestamp], t.Value, t.FK_ConfigId
FROM myTable AS t
WHERE t.[Timestamp] <= d.currentDate and t.FK_ConfigId in (208812, 208809, 208815)
ORDER BY t.[Timestamp] DESC, t.Value, t.FK_ConfigId
) AS t
This gives an output like so:
currentDate value FK_ConfigId
1/1/2015 12:15 2 208809
1/1/2015 12:30 5 208815
1/1/2015 12:45 1 208815
But actually I need to have one record per timestamp per unique FK_ConfigId that I specify in a list. Right now I am only getting one record per timestamp regardless of the config ID. The output I want:
currentDate value FK_ConfigId
1/1/2015 12:15 2 208809
1/1/2015 12:15 4 208815
1/1/2015 12:30 5 208809
1/1/2015 12:30 1 208815
How could I achieve this?

Answer 1

Try this and tell me what you think:
DECLARE #StartDateTime datetime = '2015-07-13 14:00:00',
#EndDateTime datetime = '2015-07-13 16:00:00';
WITH JumpsOf15 AS (
SELECT Step = Row_Number() OVER (ORDER BY (SELECT 1)) * 15
FROM sys.objects
),
Dates AS (
SELECT currentDate = DateAdd(minute, Step, #StartDateTime)
FROM JumpsOf15
WHERE Step < DateDiff(minute, 0, #EndDateTime - #StartDateTime)
)
SELECT
d.currentDate,
t.ConfigId,
t.Value
FROM
Dates d
CROSS JOIN (VALUES
(208812), (208809), (208815)
) c (ConfigId)
OUTER APPLY (
SELECT TOP 1
t.[Timestamp],
t.Value,
t.FK_ConfigId
FROM myTable t
WHERE
d.currentDate >= t.[Timestamp]
AND c.ConfigId = t.FK_ConfigId
ORDER BY
t.[Timestamp] DESC,
t.Value
) t
;