candidate_skills(candidate_id, skill) and required_skills(skill)

Return the candidate_id of everyone who has every skill in required_skills. Having extra skills is fine.

candidate_skills contains duplicate rows, and they must not make a candidate look more qualified than they are.

Tables

candidate_skills

candidate_id  skill
------------  ------
1             sql
1             python
1             excel
2             sql
2             sql
3             python
4             sql
4             python

required_skills

skill
------
sql
python

Expected result

candidate_id
------------
1
4