Query to show a month in which status changed

Question

I have a table with columns containing member_name, Month_report_generated, and Current_status.
There is a month report for every month in the year showing the member's status in that month, and the status can change in any month.
I am trying to write a query that finds the month in which a member's status changed. I was thinking that the way to do this would be to find the max month that showed the member at the old status, and therefore that would be the month before the new status came into effect.
I am not sure how to write this query and any help would be appreciated.
Thanks

Answer 1

It would be helpful if you could have posted your sample data along.
Anyways, Maybe something like:
SQL> WITH TEST_TAB
  2         AS (SELECT   'ABC' member_name,
  3                      'Jan2009' Month_report_generated,
  4                      'Y' Current_status
  5               FROM   DUAL
  6             UNION ALL
  7             SELECT   'ABC' member_name,
  8                      'Feb2009' Month_report_generated,
  9                      'Y' Current_status
10               FROM   DUAL
11             UNION ALL
12             SELECT   'ABC' member_name,
13                      'Mar2009' Month_report_generated,
14                      'N' Current_status
15               FROM   DUAL
16             UNION ALL
17             SELECT   'ABC' member_name,
18                      'Apr2009' Month_report_generated,
19                      'N' Current_status
20               FROM   DUAL
21             UNION ALL
22             SELECT   'ABC' member_name,
23                      'May2009' Month_report_generated,
24                      'Y' Current_status
25               FROM   DUAL)
26               -- end test data
27  SELECT   *
28    FROM   TEST_TAB
29  /
MEM MONTH_R C
ABC Jan2009 Y
ABC Feb2009 Y
ABC Mar2009 N  -- Status changed in this month
ABC Apr2009 N
ABC May2009 Y -- Status changed in this month
5 rows selected.
SQL> WITH TEST_TAB
  2         AS (SELECT   'ABC' member_name,
  3                      'Jan2009' Month_report_generated,
  4                      'Y' Current_status
  5               FROM   DUAL
  6             UNION ALL
  7             SELECT   'ABC' member_name,
  8                      'Feb2009' Month_report_generated,
  9                      'Y' Current_status
10               FROM   DUAL
11             UNION ALL
12             SELECT   'ABC' member_name,
13                      'Mar2009' Month_report_generated,
14                      'N' Current_status
15               FROM   DUAL
16             UNION ALL
17             SELECT   'ABC' member_name,
18                      'Apr2009' Month_report_generated,
19                      'N' Current_status
20               FROM   DUAL
21             UNION ALL
22             SELECT   'ABC' member_name,
23                      'May2009' Month_report_generated,
24                      'Y' Current_status
25               FROM   DUAL)
26               -- end test data
27  SELECT   member_name,
28           lead_month month_report_generated,
29           lead_status current_status
30    FROM   (SELECT   member_name,
31                     month_report_generated,
32                     LEAD (
33                        Month_report_generated,
34                        1,
35                        Month_report_generated
36                     )
37                        OVER (
38                           PARTITION BY member_name
39                           ORDER BY TO_DATE (Month_report_generated, 'MonYYYY')
40                        )
41                        lead_month,
42                     LEAD (
43                        Current_status,
44                        1,
45                        Current_status
46                     )
47                        OVER (
48                           PARTITION BY member_name
49                           ORDER BY TO_DATE (Month_report_generated, 'MonYYYY')
50                        )
51                        lead_status,
52                     current_status
53              FROM   test_tab) a1
54   WHERE   a1.lead_status <> a1.current_status
55  /
MEM MONTH_R C
ABC Mar2009 N
ABC May2009 Y
2 rows selected.
SQL>Regards,
Jo