CASE
           WHEN DATEDIFF(MINUTE,a.start_time, a.end_time) = 0
             THEN '0 min' + ' ' + CAST(CAST(a.execution_duration/1000.0 AS NUMERIC(6,2)) AS VARCHAR(20)) + ' ' + N'сек'
           ELSE
                CASE
                  WHEN DATEDIFF(MINUTE,a.start_time, a.end_time) > 60
                    THEN CAST(DATEDIFF(MINUTE,a.start_time, a.end_time) / 60 AS VARCHAR(20)) + ' ' + N'ч.' + CAST(DATEDIFF(MINUTE,a.start_time, a.end_time) % 60 AS VARCHAR(20)) + ' ' + N'мин.'
                  ELSE CAST(DATEDIFF(MINUTE,a.start_time, a.end_time) AS VARCHAR(20)) + ' ' + N'мин.'
                END
        END AS [Продолжительность]