DECLARE @calendar TABLE (dateTime DATETIME)
DECLARE @daTetime DATETIME = '2020-07-08'
SET NOCOUNT ON
WHILE CAST(@dateTime AS DATE) < '2020-11-08'
BEGIN
INSERT INTO @calendar (dateTime) VALUES (@dateTime)
SET @dateTime = DATEADD(MINUTE,5,@dateTime)
END
SET NOCOUNT OFF
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
;with tab as (
SELECT a.[Session Id]
     , a.[Participant Id]
     , a.[Full Name]
     , a.[UserAgent]
     , SessionStartTime
     , SessionEndTime
     , a.[Role]
FROM(
            SELECT  [Session Id]
                  , [Participant Id]
                  , [Full Name]
                  , [UserAgent]
                  , [UTC Event Timestamp] as SessionStartTime
                  , [Action]
                  , [Role]
            FROM [dbo].[meetings]
            WHERE Action = 'joined'
      ) s join (
            SELECT [Session Id]
                  ,[Participant Id]
                  ,[Full Name]
                  ,[UserAgent]
                  ,[UTC Event Timestamp] as SessionEndTime
                  ,[Action]
                  ,[Role]
            FROM [dbo].[meetings]
            WHERE Action = 'Left'
      ) a on s.[Session Id] = a.[Session Id]
)


SELECT *,
DATEDIFF(SECOND,
CASE WHEN e.SessionStartTime >= c.dateTime THEN e.SessionStartTime
     WHEN e.SessionStartTime <  c.dateTime THEN c.dateTime
END,
CASE WHEN e.SessionEndTime <= DATEADD(MINUTE,5,c.dateTime) THEN e.SessionEndTime
     WHEN e.SessionEndTime >  DATEADD(MINUTE,5,c.dateTime) THEN DATEADD(MINUTE,5,c.dateTime)
END
) as granularity
  FROM @calendar c
    LEFT OUTER JOIN tab e
      ON e.SessionStartTime BETWEEN c.dateTime AND DATEADD(MINUTE,5,c.dateTime)
      OR e.SessionEndTime BETWEEN c.dateTime AND DATEADD(MINUTE,5,c.dateTime)
      OR c.dateTime BETWEEN e.SessionStartTime AND e.SessionEndTime
      where [Session Id] is not null