Leetcode: Winning Candidate

Winning Candidate

Similar Problems:

• Review: SQL Problems
• Tag: #sql

Table: Candidate

+-----+---------+
| id  | Name    |
+-----+---------+
| 1   | A       |
| 2   | B       |
| 3   | C       |
| 4   | D       |
| 5   | E       |
+-----+---------+  

Table: Vote

+-----+--------------+
| id  | CandidateId  |
+-----+--------------+
| 1   |     2        |
| 2   |     4        |
| 3   |     3        |
| 4   |     2        |
| 5   |     5        |
+-----+--------------+

id is the auto-increment primary key,
CandidateId is the id appeared in Candidate table.
Write a sql to find the name of the winning candidate, the above example will return the winner B.

+------+
| Name |
+------+
| B    |
+------+

Notes:
You may assume there is no tie, in other words there will be at most one winning candidate.

Github: code.dennyzhang.com

Credits To: leetcode.com

Leave me comments, if you have better ways to solve.

## Blog link: https://code.dennyzhang.com/winning-candidate
select Name
from Candidate where
id = (select CandidateId
     from Vote
     group by CandidateId
     order by count(1) desc
     limit 1)

## Assumtion: if we have two candidates with the same votes, we choose the one who get the first vote
# select Name
# from Candidate inner join
#     (select CandidateId
#     from Vote
#     group by CandidateId
#     order by count(1) desc
#     limit 1) as t
# on Candidate.id = t.CandidateId