関数を使用して 2 つの日付値間の年、月、日の差を返すにはどうすればよいでしょうか?

mysql> CREATE FUNCTION date_difference(Date1 DATE, date2 DATE) RETURNS VARCHAR(30)
   -> RETURN CONCAT(
   -> @years := TIMESTAMPDIFF(YEAR, date1, date2),IF (@years = 1, ' year, ', ' years, '),
   -> @months := TIMESTAMPDIFF(MONTH, DATE_ADD(date1, INTERVAL @years YEAR), date2),IF (@months = 1, ' month, ', ' months, '),
   -> @days := TIMESTAMPDIFF(DAY, DATE_ADD(date1, INTERVAL @years * 12 + @months MONTH), date2),IF (@days = 1, ' day', ' days')) ;
   Query OK, 0 rows affected (0.00 sec)

mysql> Select date_difference('2015-11-16','2016-12-17') AS Difference;
+------------------------+
| Difference             |
+------------------------+
| 1 year, 1 month, 1 day |
+------------------------+
1 row in set (0.00 sec)