Delete Duplicate Emails

    Write a SQL query to delete all duplicate e-mail entries in a table named person, keeping unique emails based on I    TS 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 has the following rows: +----+------------------+ | Id |    Email | +----+------------------+    | 1 |    [Email protected] | | 2 |    [Email protected] | +----+------------------+ Find First, and then delete the delete from person where (id,email) not in (select Id,email from person GROUP by E    Mail order by Email); ERROR 1093 (HY000): You can ' t specify the target table ' person ' for the update in FROM clause means: You cannot query the delete condition in a table and then delete the update in this list    。 Workaround: Create a temporary table, then find the delete condition, and finally delete the update select * from the person P1 INNER JOIN person P2 WHERE p1. Email = P2. Email and P1. Id > P2.    Id; +------+---------+------+---------+    | ID | Email | ID |    Email |    +------+---------+------+---------+    | 3 |    [Email protected] | 1 |    [Email protected] |    | 6 |    [Email protected] | 1 |    [Email protected] |    | 4 |    [Email protected] | 2 |    [Email protected] |    | 6 |    [Email protected] | 3 |    [Email protected] | +------+---------+------+---------+ delete p1 from person p1 inner join person p2 where P1.email = P2.email and P1.id & Gt    P2.id;    or delete P1 from P1 using the person P1 inner The join person p2 where P1.email = P2.email and p1.id > p2.id; [MySQL Delete multiple table association Delete] (http://blog.csdn.net/havedream_one/article/details/45421017)

Delete Duplicate Emails