SELECT t2.username,t1.sql_id ,t1.disk_reads_total, t1.executions_total,
    t1.disk_reads_total / DECODE(t1.executions_total, 0, 1, t1.executions_total) as exec_ratio
  FROM dba_hist_sqlstat t1, dba_users t2
  WHERE t1.parsing_user_id = t2.user_id
    AND t.snap_id between &Begin_Snap and &End_Snap
  ORDER BY snap_id,t1.disk_reads_total