Combine Queries where one is recursive - sql

Question

I have a recursive query that creates a row for each hour of the previous month as follows;
WITH a AS (
SELECT DATEADD(MONTH, DATEDIFF(MONTH, 0, GETDATE())-1, 0) AS [DateTime]
UNION ALL
SELECT dateadd(hour, 1, [DateTime])
FROM a
WHERE dateadd(hour, 1, [DateTime]) < EOMONTH(GETDATE(), -1)
)
SELECT
a.*
FROM a
OPTION (maxrecursion 0);
This produces these results;
DateTime
2020-11-01 00:00:00.000
2020-11-01 01:00:00.000
2020-11-01 02:00:00.000
etc.....
Next I have a query that calculates the number of calls per customer, per hour, for the previous month, as a 4 week average as follows;
SELECT
DATEADD(hour, DATEDIFF(hour, 0,
DATEADD(minute, 30 - DATEPART(minute, Timestamp + '00:30:00.000'),
Timestamp)), 0) as RoundedToHour,
Campaign,
COUNT(*)/4 AS Average
FROM [Reporting].[dbo].[New_Five9_CallLog] WITH (NOLOCK)
WHERE DATEDIFF(mm, Timestamp, GETDATE()) = 1
AND Call_Type = 'Inbound'
GROUP BY Campaign,
DATEADD(hour, DATEDIFF(hour, 0,
DATEADD(minute, 30 - DATEPART(minute, Timestamp + '00:30:00.000'),
Timestamp)), 0)
This produces the following results;
RoundedToHour Campaign Average
2020-11-01 02:00:00.000 Client1 0
2020-11-01 04:00:00.000 Client2 2
etc....
What I am having trouble doing is combining these two. My initial thoughts were to use a CTE of the recursive query as basically a where clause in my second query, but since you have to use a WITH for CTE's, and I have to use a WITH for my recursive query, that won't directly work, because you can't have nested WITH's.
My final result I am looking for is a single query that produces the 4 week average of calls for each hour of the previous month, for each client. I am open to changing how I am doing any of this if someone has a better suggestion on how to reach my ultimate goal.

Answer 1

You can't declare a CTE in a sub-query but you can declare multiple CTEs together. So declare both and then LEFT JOIN them.
WITH a AS (
SELECT DATEADD(MONTH, DATEDIFF(MONTH, 0, GETDATE())-1, 0) AS [DateTime]
UNION ALL
SELECT dateadd(hour, 1, [DateTime])
FROM a
WHERE dateadd(hour, 1, [DateTime]) < EOMONTH(GETDATE(), -1)
), b AS (
SELECT
DATEADD(hour, DATEDIFF(hour, 0,
DATEADD(minute, 30 - DATEPART(minute, Timestamp + '00:30:00.000'),
Timestamp)), 0) as RoundedToHour,
Campaign,
COUNT(*)/4 AS Average
FROM [Reporting].[dbo].[New_Five9_CallLog] WITH (NOLOCK)
WHERE DATEDIFF(mm, Timestamp, GETDATE()) = 1
AND Call_Type = 'Inbound'
GROUP BY Campaign,
DATEADD(hour, DATEDIFF(hour, 0,
DATEADD(minute, 30 - DATEPART(minute, Timestamp + '00:30:00.000'),
Timestamp)), 0)
)
SELECT a.*, b.*
FROM a
LEFT JOIN b on b.RoundedToHour = a.DateTime
OPTION (maxrecursion 0);