¿Cómo combinar dos columnas MySQL en una columna?

En SQL mismo puedes hacerlo usando UNION . Y usa ORDER BY para toda la consulta!

SELECT `title1` AS `title`, `type`
FROM `table`
UNION
SELECT `title2` AS `title`, `type`
FROM `table`
ORDER BY `title` ASC

Salida

+-------+------+
| TITLE | TYPE |
+-------+------+
|  asd1 |    7 |
|  asd2 |    7 |
|  qwe1 |    3 |
|  qwe2 |    3 |
+-------+------+

Violín:http://sqlfiddle.com/#!2/ff9cf/1