SQL delete all rows except some ones

Question

I have a table with the following columns (of urls):

 [id,url,visited,timestamp]
 Types:[int,string,int,long]

I want to:

Delete all urls except 10 unvisited priorizing higher timestamp (or delete all if all are visited for example)

Its posible to do that in a single query? Anyway whats the best query (queries) for doing it?

Thanks in advance

Answer 1

I don't think TOP works in sqlite -- need to use LIMIT

DELETE FROM mytable WHERE id NOT IN ( 
   SELECT id FROM mytable  
   WHERE visited = false 
   ORDER BY timestamp DESC
   LIMIT 10  
   )