WITH timeSequence AS
(
    SELECT
       CONVERT(datetime, '2019-11-15T14:45:50Z', 127) AS StartRange
    UNION ALL
    SELECT
      DATEADD(SECOND, 60, StartRange)
    FROM timeSequence
    WHERE DATEADD(SECOND, 60, StartRange) < CONVERT(datetime, '2019-11-15T14:50:50Z', 127)
)
SELECT
  DATEADD(SECOND, FLOOR(DATEDIFF(second, '1970-01-01', ts.StartRange)/60)*60, '1970-01-01') AS time,
  'running_items' as metric,
  COUNT(ri.RunItemId) as value
FROM timeSequence AS ts
LEFT JOIN proj.RunItem AS ri
ON
    ri.Start BETWEEN '2019-11-15T14:45:50Z' AND '2019-11-15T14:50:50Z'
    AND
    ri.Finish BETWEEN '2019-11-15T14:45:50Z' AND '2019-11-15T14:50:50Z'
    AND
    ts.StartRange BETWEEN ri.Start AND ri.Finish AND ri.State IN (1,2,3)
WHERE
  ts.StartRange BETWEEN '2019-11-15T14:45:50Z' AND '2019-11-15T14:50:50Z'
GROUP BY  1, 2
ORDER BY
  ts.StartRange ASC