大数据第45天—Mysql练习题16- 当选者-杨大伟

需求：请编写 sql 语句来找到当选者（CandidateId）的名字

展示效果：

Name

B

Create table If Not Exists Candidate (id int, Name varchar(255));
Create table If Not Exists Vote (id int, CandidateId int);

insert into Candidate (id, Name) values (1, 'A');
insert into Candidate (id, Name) values (2, 'B');
insert into Candidate (id, Name) values (3, 'C');
insert into Candidate (id, Name) values (4, 'D');
insert into Candidate (id, Name) values (5, 'E');

insert into Vote (id, CandidateId) values (1, 2);
insert into Vote (id, CandidateId) values (2, 44);
insert into Vote (id, CandidateId) values (3, 3);
insert into Vote (id, CandidateId) values (4, 2);
insert into Vote (id, CandidateId) values (5, 5);

最终SQL:

SELECT
    name AS 'Name'
FROM
    Candidate
JOIN
    (SELECT
        Candidateid
    FROM
        Vote
    GROUP BY 
        Candidateid
    ORDER BY 
        COUNT(*) DESC
    LIMIT 1
    ) AS winner
WHERE
    Candidate.id = winner.Candidateid;