Leetcode 196. Delete duplicate Emails. (Database)

# Write your MySQL query statement below
SELECT Email FROM Person GROUP BY Email HAVING COUNT(*) > 1

方法1： join再删掉不需要的。

DELETE p2 FROM Person p1 JOIN Person p2 
ON p2.Email = p1.Email WHERE p2.Id > p1.Id;

方法2： 不用join, 用where:

DELETE p2 FROM Person p1, Person p2
WHERE p1.Email = p2.Email AND p2.Id > p1.Id;

Leetcode 196. Delete duplicate Emails. (Database)

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