196. Delete Duplicate Emails (Easy)
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 delete statement.
Solutions
DELETE
p1
FROM
Person p1, Person p2
WHERE
p1.Email = p2.Email AND p1.Id > p2.Id;