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

What are the student ids for students over 20 years old?
SELECT stuid FROM student WHERE age > 20
SELECT "stuid" FROM "student" WHERE "age" > 20