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

Find the ids of the students who participate in Canoeing and Kayaking.
SELECT T1.stuid FROM participates_in AS T1 JOIN activity AS T2 ON T2.actid = T2.actid WHERE T2.activity_name = 'Canoeing' INTERSECT SELECT T1.stuid FROM participates_in AS T1 JOIN activity AS T2 ON T2.actid = T2.actid WHERE T2.activity_name = 'Kayaking'
SELECT "T1"."stuid" FROM "participates_in" AS "T1" JOIN "activity" AS "T2" ON "T2"."actid" = "T2"."actid" AND "T2"."activity_name" = 'Canoeing' INTERSECT SELECT "T1"."stuid" FROM "participates_in" AS "T1" JOIN "activity" AS "T2" ON "T2"."actid" = "T2"."actid" AND "T2"."activity_name" = 'Kayaking'