Remove duplicate rows in a table having no primary key

Question

I have a table item that contains items like

name
------
alpha
alpha 
beta
charlie
charlie

In this case how would I delete duplicate rows but one record should remain. The above table does not have any primary key.

Answer 1

Try this

DELETE FROM item WHERE GREATEST(0,@num := IF(NAME = @NAME, @num + 1, 0),LEAST(0, LENGTH(@NAME := NAME)))>0