How to find gaps in data?

Question

Hi!
I have the following problem.
Data:
range_id actual_nr
AAA 001AAA
AAA 002AAA
AAA 003AAA
AAA 006AAA
AAA 007AAA
AAA 009AAA
BBB 001BBB
BBB 002BBB
etc.
I have to get report in the following form
from to nr_of_rows
001AAA 003AAA 3
006AAA 007AAA 2
009AAA 1
001BBB 002BBB 2
etc.
As you can see if there is a gap in sequence then I have to calculate how many rows were in sequence before the gap.
Can somebody give me some hints or even working statement?

Answer 1

How's this?
WITH
     Sample_Data
AS
      SELECT 'AAA' range_id, '001AAA' actual_nr FROM Dual UNION ALL
      SELECT 'AAA' range_id, '002AAA' actual_nr FROM Dual UNION ALL
      SELECT 'AAA' range_id, '003AAA' actual_nr FROM Dual UNION ALL
      SELECT 'AAA' range_id, '006AAA' actual_nr FROM Dual UNION ALL
      SELECT 'AAA' range_id, '007AAA' actual_nr FROM Dual UNION ALL
      SELECT 'AAA' range_id, '009AAA' actual_nr FROM Dual UNION ALL
      SELECT 'BBB' range_id, '001BBB' actual_nr FROM Dual UNION ALL
      SELECT 'BBB' range_id, '002BBB' actual_nr FROM Dual
SELECT
     MIN(actual_nr_start)     actual_nr_start,
     actual_nr_finish,
     MAX(Total)
FROM
      SELECT
          range_id,
          MIN(actual_nr)     actual_nr_start,
          MAX(actual_nr)     actual_nr_finish,
          MAX(Level)     Total
      FROM
          Sample_Data
      CONNECT BY
          range_id          = PRIOR range_id
         AND     substr(actual_nr, 1, 3)     = substr(PRIOR actual_nr, 1, 3) + 1
      GROUP BY
          range_id,
          CONNECT_BY_ROOT actual_nr
GROUP BY
     actual_nr_finish
ORDER BY
     SubStr(actual_nr_start, -3),
     actual_nr_start;Message was edited by:
Brian Tkatch 2
consolidated two levels.