add 574

Author: fishercoder1534

README.md

@@ -609,6 +609,7 @@ Your ideas/fixes/algorithms are more than welcome!
 |584|[Find Customer Referee](https://leetcode.com/problems/find-customer-referee/)|[Solution](../master/database/_584.java) | || Easy|
 |580|[Count Student Number in Departments](https://leetcode.com/problems/count-student-number-in-departments/)|[Solution](../master/database/_580.sql) | || Medium | Left Join
 |577|[Employee Bonus](https://leetcode.com/problems/employee-bonus/)|[Solution](../master/database/_577.sql) | || Easy |
+|574|[Winning Candidate](https://leetcode.com/problems/winning-candidate/)|[Solution](../master/database/_574.sql) | || Medium |
 |197|[Rising Temperature](https://leetcode.com/problems/rising-temperature/)|[Solution](../master/database/_197.sql)| O(n^2)|O(n) | Easy|
 |196|[Delete Duplicate Emails](https://leetcode.com/problems/delete-duplicate-emails/)|[Solution](../master/database/_196.sql)| O(n^2)|O(n) | Easy|
 |184|[Department Highest Salary](https://leetcode.com/problems/department-highest-salary)|[Solution](../master/database/_184.sql)| O(n^2)|O(n) | Medium|

database/_574.sql

@@ -0,0 +1,37 @@
+--574. Winning Candidate
+--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.
+
+select Name from Candidate as Name where id =
+(select CandidateId from Vote group by CandidateId order by count(CandidateId) desc limit 1);