https://leetcode.com/problems/delete-duplicate-emails/
Write a SQL query to delete all duplicate email entries in a table named Person, keeping only unique emails based on its smallest Id.
+----+------------------+ | Id | Email | +----+------------------+ | 1 | john@example.com | | 2 | bob@example.com | | 3 | john@example.com | +----+------------------+ Id is the primary key column for this table.
For example, after running your query, the above Person table should have the following rows:
+----+------------------+ | Id | Email | +----+------------------+ | 1 | john@example.com | | 2 | bob@example.com | +----+------------------+
Note:
Your output is the whole Person table after executing your sql. Use deletestatement.
代码：
# Write your MySQL query statement below DELETE t1 FROM Person t1, Person t2 WHERE t1.Email = t2.Email AND t1.Id > t2.Id
FH
#Leetcode# 196. Delete Duplicate Emails
原文：https://www.cnblogs.com/zlrrrr/p/10848801.html