Write a SQL query to delete all duplicate email entries in a table, keeping only unique emails based on its smallest 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 have the following rows:
DELETE p1 FROM Person p1, Person p2 WHERE p1.Email = p2.Email AND p1.Id > p2.Id
- Join the table on itself by the Email
- From this results filter the records that have p1.Id>p2.ID
Delete FROM Person WHERE Id not in ( Select A.Id From(Select min(Id) as Id from Person GROUP BY Email) A )