# | Title | Solution | Difficulty |
---|---|---|---|
176 | Second Highest Salary | MySQL, Oracle, PostgreSQL | Easy |
183 | Customers Who Never Order | MySQL | Easy |
185 | Department Top Three Salaries | Oracle, PostgreSQL | Hard |
578 | Get Highest Answer Rate Question | MySQL | Median |
597 | Friend Requests I: Overall Acceptance Rate | MySQL | Easy |
602 | Friend Requests II: Who Has the Most Friends | MySQL | Median |
511 | Game Play Analysis I | MySQL | Easy |
512 | Game Play Analysis II | MySQL | Easy |
534 | Game Play Analysis III | MySQL | Medium |
550 | Game Play Analysis IV | PostgreSQL | Medium |
569 | Median Employee Salary | MySQL | Hard |
570 | Managers with at Least 5 Direct Reports | MySQL | Medium |
574 | Winning Candidate | MySQL | Medium |
577 | Employee Bonus | MySQL | Easy |
578 | Get Highest Answer Rate Question | MySQL | Medium |
580 | Count Student Number in Departments | MySQL | Medium |
584 | Find Customer Referee | MySQL | Easy |
585 | Investments in 2016 | MySQL | Medium |
# | Problem | Solution | Concept/Comment |
---|---|---|---|
1 | User Status | MySQL | |
2 | Recommend pages your friends liked | MySQL | |
3 | Advertiser spend and ROI metrics | MySQL | subquery |
4 | Friends' Messages | Postgres | |
5 | Content Actions (Comments per Story) | MySQL, PostgreSQL | left join |
6 | Click Through Rate | MySQL, Postgres | group by, sum |
7 | Friend Acceptance Rate Trending | PostgreSQL | subquery(left join) group by |
8 | Carrier | MySQL | case study |
9 | Comments on Post | MySQL | similar to #5 |
# | Problem | Solution | Concept/Comment |
---|---|---|---|
1 | customers not making purchase | MySQL |
# | Problem | Solution | Concept/Comment |
---|---|---|---|
1 | Video | Postgres | sum, find max |