Deleting a large number of records from a database without locking it (for ages) #SQL

If you have a large database, with millions of rows, and you need to run an batch operation on it, like deleting lots of old records, then you’ll quickly find that the operation often will lock the table, and prevent users get at their data – as well as bloating the transaction log table. So, the trick is to break it down into manageable chunks. Let’s say the operation I want to run is this; delete from log where success=0