Вы можете сделать это с помощью запроса, как это:
SELECT Years
FROM (
SELECT yearIn AS Years FROM yourTable
UNION ALL
SELECT yearOut FROM yourTable
) y
ORDER BY Years;
вы также можете использовать это без подзапроса
SELECT yearIn AS Years FROM yourTable
UNION ALL
SELECT yearOut FROM yourTable
ORDER BY Years;
EXPLAIN и без подзапроса
mysql> EXPLAIN SELECT Years
-> FROM (
-> SELECT yearIn AS Years FROM yourTable
-> UNION ALL
-> SELECT yearOut FROM yourTable
->) y
-> ORDER BY Years;
+----+-------------+------------+------------+------+---------------+------+---------+------+------+----------+----------------+
| id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
+----+-------------+------------+------------+------+---------------+------+---------+------+------+----------+----------------+
| 1 | PRIMARY | <derived2> | NULL | ALL | NULL | NULL | NULL | NULL | 6 | 100.00 | Using filesort |
| 2 | DERIVED | yourTable | NULL | ALL | NULL | NULL | NULL | NULL | 3 | 100.00 | NULL |
| 3 | UNION | yourTable | NULL | ALL | NULL | NULL | NULL | NULL | 3 | 100.00 | NULL |
+----+-------------+------------+------------+------+---------------+------+---------+------+------+----------+----------------+
3 rows in set, 1 warning (0,00 sec)
mysql>
mysql> EXPLAIN SELECT yearIn AS Years FROM yourTable
-> UNION ALL
-> SELECT yearOut FROM yourTable
-> ORDER BY Years;
+----+--------------+------------+------------+------+---------------+------+---------+------+------+----------+---------------------------------+
| id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
+----+--------------+------------+------------+------+---------------+------+---------+------+------+----------+---------------------------------+
| 1 | PRIMARY | yourTable | NULL | ALL | NULL | NULL | NULL | NULL | 3 | 100.00 | NULL |
| 2 | UNION | yourTable | NULL | ALL | NULL | NULL | NULL | NULL | 3 | 100.00 | NULL |
| NULL | UNION RESULT | <union1,2> | NULL | ALL | NULL | NULL | NULL | NULL | NULL | NULL | Using temporary; Using filesort |
+----+--------------+------------+------------+------+---------------+------+---------+------+------+----------+---------------------------------+
3 rows in set, 1 warning (0,00 sec)
mysql>
Почему подзапрос? Кроме того, кто сказал, что мы хотим дублировать? – shmosel
@shmosel - который дублирует? –
В этом примере нет, но это может быть возможно. – shmosel