Leetcode 196. Delete duplicate Emails. (Database)

Write a SQL query to delete all duplicate e-mail entries in a table named person, keeping unique emails based on its s Mallest Id.

+----+------------------+| Id | Email            |+----+------------------+| 1  | [Email protected] | | 2  | [email protected]  | | 3  | [Email protected] |+----+------------------+

Id is the primary key, column for this table.
For example, after running your query, the above person table should has the following rows:

+----+------------------+| Id | Email            |+----+------------------+| 1  | [Email protected] | | 2  | [email protected]  | +----+------------------+

Two methods don't quite understand, t,p?

 delete  from  person where  Id not  in   ( select  Id from  (select  min  (ID) ID from  person group  by  Email) p); 

# Write Your MySQL query statement below SELECT  from GROUP  by  having COUNT (*>1

Method 1:join and then delete the unwanted.

DELETE  from JOIN  on=WHERE> p1. Id;

Method 2: Do not join, with where:

DELETE  from Person p1, person p2 WHERE =  and > p1. Id;

Leetcode 196. Delete duplicate Emails. (Database)