CREATE TABLE allergy_type (allergy CLOB, allergytype CLOB)
CREATE TABLE student (stuid NUMBER, lname CLOB, fname CLOB, age NUMBER, sex CLOB, major NUMBER, advisor NUMBER, city_code CLOB)
CREATE TABLE has_allergy (stuid NUMBER, allergy CLOB)

Which allergy type is the least common?
SELECT allergytype FROM allergy_type GROUP BY allergytype ORDER BY COUNT(*) LIMIT 1
SELECT "allergytype" FROM "allergy_type" GROUP BY "allergytype" ORDER BY COUNT(*) FETCH FIRST 1 ROWS ONLY