SQLite 3.27

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CREATE TABLE tablename (`observation_date` TEXT, `item_date` TEXT, `item_value` INTEGER);
✓
INSERT INTO tablename (`observation_date`, `item_date`, `item_value`) VALUES
  ('2015-01-01', '2012-12-31', '0'),
  ('2015-01-01', '2013-03-31', '1'),
  ('2015-01-01', '2013-06-30', '2'),
  ('2015-01-01', '2013-09-30', '3'),
  ('2015-01-01', '2013-12-31', '4'),
  ('2015-01-01', '2014-03-31', '5'),
  ('2015-01-01', '2014-06-30', '6'),
  ('2015-01-01', '2014-09-30', '7'),
  ('2016-01-01', '2013-09-30', '8'),
  ('2016-01-01', '2013-12-31', '9'),
  ('2016-01-01', '2014-03-31', '10'),
  ('2016-01-01', '2014-06-30', '11'),
  ('2016-01-01', '2014-09-30', '12'),
  ('2016-01-01', '2014-12-31', '13'),
  ('2016-01-01', '2015-03-31', '14'),
  ('2016-01-01', '2015-06-30', '15'),
  ('2016-01-01', '2015-09-30', '16');
✓
SELECT t1.*
FROM tablename t1
WHERE t1.item_date = (
  SELECT DATE(MAX(t2.item_date), '-' || '1' || ' year') 
  FROM tablename t2 
  WHERE t2.observation_date = t1.observation_date
);


observation_date
item_date
item_value


2015-01-01
2013-09-30
3

2016-01-01
2014-09-30
12