Number of Transactions (per second)

WITH
    hist_snaps
    AS
        (SELECT instance_number,
                snap_id,
                ROUND (begin_interval_time, 'MI') begin_snap_time,
                ROUND (end_interval_time, 'MI') end_snap_time,
                  (  begin_interval_time
                   + 0
                   - LAG (begin_interval_time + 0)
                         OVER (PARTITION BY dbid, instance_number
                               ORDER BY snap_id))
                * 86400                              diff_time
           FROM dba_hist_snapshot),
    hist_stats
    AS
        (SELECT dbid,
                instance_number,
                snap_id,
                stat_name,
                  VALUE
                - LAG (VALUE)
                      OVER (PARTITION BY dbid, instance_number, stat_name
                            ORDER BY snap_id)    delta_value
           FROM dba_hist_sysstat
          WHERE stat_name IN ('user commits', 'user rollbacks'))
  SELECT sn.begin_snap_time,
         sn.end_snap_time,
         sn.instance_number,
         ROUND (SUM (delta_value) / 3600)     "TRANSACTIONS/S"
    FROM hist_snaps sn, hist_stats st
   WHERE st.instance_number = sn.instance_number
     AND st.snap_id = sn.snap_id
     AND sn.diff_time IS NOT NULL
     AND sn.instance_number = 1
     AND TO_CHAR (sn.end_snap_time, 'yyyy-mm-dd') = TO_CHAR (sysdate-1, 'yyyy-mm-dd')
GROUP BY sn.begin_snap_time, sn.end_snap_time, sn.instance_number
ORDER BY 1;