MySql - ON DUPLICATE KEY INSERT

With ON DUPLICATE KEY UPDATE, you cannot insert into another table - nor is there an alternative function available.

Two custom/alternative ways you can accomplish this:

1. Using a stored procedure as outlined in the accepted answer to this question: MySQL ON DUPLICATE KEY insert into an audit or log table

2. Creating a trigger that logged every INSERT for your table into another table and querying the table full of "logs" for any duplicates.

Something similar to this should work:

CREATE TABLE insert_logs (
    id int not null
);

delimiter |
CREATE TRIGGER insert_logs_trigger BEFORE INSERT ON your_table
    FOR EACH ROW BEGIN
        INSERT INTO insert_logs SET id = NEW.id;
    END;
|

To get a list of the duplicates in the table, you could us:

SELECT id FROM insert_logs HAVING COUNT(id) > 1 GROUP BY id;