题目

代码部分一（1433ms 50.12%）

# Write your MySQL query statement below
DELETE
    a
    FROM Person a,Person b
    WHERE a.Email=b.Email AND a.Id>b.Id;

代码部分二（933ms 90.55%）

# Write your MySQL query statement below
DELETE
FROM Person
WHERE 
     Id NOT IN(
     SELECT Id
     FROM (SELECT MIN(Id) AS Id FROM Person GROUP BY Email) AS p
     )