Quickly duplicate a row in MySQL

/*
Duplicate row 58 from mytable
*/
CREATE TEMPORARY TABLE tmptable  SELECT * FROM mytable WHERE id = 58;
 
/*
Change the unique key
*/
UPDATE tmptable SET id=0; 
 
/* 
Insert the duplicate row into the original table
*/
INSERT INTO mytable SELECT * FROM tmptable;
 
/* 
Drop the temporary table
*/
DROP TABLE tmptable;