How to Generate Date Ranges in Oracle SQL

I’ve just come across an interesting SQL question here on CodeRanch. How to generate date ranges in SQL, given any input date. The question didn’t specify the SQL dialect, so let’s choose Oracle SQL, which features the awesome CONNECT BY clause. The requirements specify that given any input date:

• Date ranges span 12 months
• The first date range starts at the input date
• The last date range includes today
• Subsequent date ranges repeat the same date

For example, using 2010-06-10 we would get:

START_DATE   END_DATE
-----------------------
2010-06-10   2011-06-10
2011-06-10   2012-06-10
2012-06-10   2013-06-10
2013-06-10   2014-06-10 <-- This includes today, 2013-07-24

It’s actually very simple:

SELECT
  add_months(input, (level - 1) * 12) start_date,
  add_months(input,  level      * 12) end_date
FROM (
  -- Set the input date here
  SELECT DATE '2010-06-10' input
  FROM DUAL
)
CONNECT BY
  add_months(input, (level - 1) * 12) < sysdate

See the SQL Fiddle here to see the above in action: http://sqlfiddle.com/#!4/d41d8/14448

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