PHP/Mysql reporting system

We have a table that has 16M+ rows. Each row is an inserted value with a userid,ltype,type (integers) and timestamp (current_time in 0000-00-00 00:00:00 format) We need a script that can crawl through this data in segments (since it is so large) and when it finds matches (more info on that below) it will then insert that data into another table. For example. for each distinct userid with ltype 0 AND type 1 we want to see the timespan between these inserts and find ones that are too close. So lets say we have the following (note these would be grouped by ltype as we have 0 and 1 ltypes and also type will always be 1 userid time ltype type 55 2011-11-20 00:02:01 1 1 55 2011-11-20 00:02:03 1 1 Userid should NEVER have more than one insert per ltype in a certain timespan (1 minute 20 seconds for example). ...Continued on project details page... ## Deliverables We have a table that has 16M+ rows. Each row is an inserted value with a userid,ltype,type (integers) and timestamp (current_time in 0000-00-00 00:00:00 format) We need a script that can crawl through this data in segments (since it is so large) and when it finds matches (more info on that below) it will then insert that data into another table. For example. for each distinct userid with ltype 0 AND type 1 we want to see the timespan between these inserts and find ones that are too close. So lets say we have the following (note these would be grouped by ltype as we have 0 and 1 ltypes and also type will always be 1 userid time ltype type 55 2011-11-20 00:02:01 1 1 55 2011-11-20 00:02:03 1 1 Userid should NEVER have more than one insert per ltype in a certain timespan (1 minute 20 seconds for example). When they have more than 30 of these (we dont want to find just one as this could be just a system error), we want this userid inserted into another table so we can further investigate this user. Using the above example if the data was... userid time ltype type 55 2011-11-20 00:02:01 1 1 55 2011-11-20 00:05:03 1 1 Then it's fine and we dont do the insert. We need to be able to specify the lytpe we are searching for when the report runs and the timespan. Incase for whatever the script is interrupted, we should use either cookies or sessions so it can resume from where it left off.