CREATE TABLE purchase (member_id DECIMAL, branch_id TEXT, year TEXT, total_pounds DECIMAL)
CREATE TABLE member (member_id DECIMAL, card_number TEXT, name TEXT, hometown TEXT, level DECIMAL)
CREATE TABLE branch (branch_id DECIMAL, name TEXT, open_year TEXT, address_road TEXT, city TEXT, membership_amount TEXT)
CREATE TABLE membership_register_branch (member_id DECIMAL, branch_id TEXT, register_year TEXT)

Show all cities without a branch having more than 100 memberships.
SELECT city FROM branch EXCEPT SELECT city FROM branch WHERE membership_amount > 100
SELECT "city" FROM "branch" EXCEPT SELECT "city" FROM "branch" WHERE "membership_amount" > 100