CREATE TABLE activity (actid DECIMAL, activity_name TEXT)
CREATE TABLE faculty (facid DECIMAL, lname TEXT, fname TEXT, rank TEXT, sex TEXT, phone DECIMAL, room TEXT, building TEXT)
CREATE TABLE participates_in (stuid DECIMAL, actid DECIMAL)
CREATE TABLE student (stuid DECIMAL, lname TEXT, fname TEXT, age DECIMAL, sex TEXT, major DECIMAL, advisor DECIMAL, city_code TEXT)
CREATE TABLE faculty_participates_in (facid DECIMAL, actid DECIMAL)

Show the ids for all the faculty members who have at least 2 students.
SELECT T1.facid FROM faculty AS T1 JOIN student AS T2 ON T1.facid = T2.advisor GROUP BY T1.facid HAVING COUNT(*) >= 2
SELECT "T1"."facid" FROM "faculty" AS "T1" JOIN "student" AS "T2" ON "T1"."facid" = "T2"."advisor" GROUP BY "T1"."facid" HAVING COUNT(*) >= 2