Extracting year and date

Question

I am working on the following query
SELECT report_date, EXTRACT (MONTH FROM report_date) FROM program_details;
SELECT a.customer_id, a.report_date as change_date
FROM program_details AS a
LEFT JOIN program_details AS b
on a. customer_id = b. customer_id
AND EXTRACT (MONTH FROM a.report_date) = EXTRACT (MONTH FROM b.report_date) - 1
AND EXTRACT (YEAR FROM a.report_date) = EXTRACT (YEAR FROM b.rpt_date )
WHERE a.code_status = 'Gold' and b.code_status = 'Plat'
AND a.report_date >= '2007-12-01 00:00:00.0'
AND a.report_date < '2009-01-01 00:00:00.0'
I have a table with customer id, yyyy-mm-dd for many years , and status as gold silver or platinum. and I need to work out the month that the status changed, and return a field as year-month.
I am trying to extract the year and date that a customer changed from gold to plat but I am not sure how date arithmetic works. I need to have output like : customer_id and year-month but I keep just getting month.
I know this is vague, but if you could help with the part of the query that delivers year and month back that would be great.
Thank you very much

Answer 1

Hi,
  1  SELECT a.customer_id, to_char(a.report_date, 'yyyy-mm') as change_date
  2* FROM program_details a
SQL> /
CUSTOMER_ID CHANGE_
          1 2009-06Bartek