Occasionally you can end up with very large databases that you need to purge old data from. Unfortunatly you cant delete all the old data in 1 chunk since it will cause you SQL server to stop serviceing anything else (and potentially fill up your logs). Below is a little script I used to delete small chunks of data quickly and efficiently.
while 1 = 1
delete top ( 1000 )
where TimeGenerated< getdate()-90 if @@rowcount = 0 BREAK end