primero debe comprender el orden por
si da el orden 1st, 2nd asc, primero ascenderá la primera columna y, dependiendo de esto, ascenderá la segunda columna. Por ejemplo,
1st 2nd
1 b
2 d
3 a
2 a
1 a
ordenar por convertir en
1st 2nd
1 a
1 b
2 a
2 d
3 a
Entonces necesita una consulta diferente
SELECT want FROM request WHERE want IS NOT NULL OR want !='' GROUP BY
want ORDER BY want ASC
SELECT teach FROM request WHERE teach IS NOT NULL OR teach !='' GROUP
BY teach ORDER BY teach ASC