Question

I believe my question was asked on SO, but I didn’t find the answer.

There is a mysql table mytable with one column mycolumn.

What is the mysql query to remove duplicates from a table?

Answer 1

Only one column without pk or another column that you can use for see if they are different?
if yes, this is a bad practice. Consider inserting a new column (number) and insert id for every record, than you can try this query:

delete from table 
where counter > 1 and inner_query.mycolumn = table.mycolumn and inner_query.col_id = table.col_id from 
(select mycolumn, col_id, count (mycolumn) counter  
 from table group by  mycolumn
) inner_query

than, you can add a primary key