Delete all rows except first N from a table having single column

Question

I need a single query. Delete all rows from the table except the top N rows. The table has only one column. Like,

|friends_name|
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Answer 1

If you don't have an id field, i suppose you use an alphabetic order.

MYSQL

DELETE FROM friends 
WHERE friends_name 
NOT IN (
    SELECT * FROM (
        SELECT friends_name 
        FROM friends 
        ORDER BY friends_name ASC
        LIMIT 10) r
)

You delete all rows exept the 10 firsts (alphabetic order)