Updating values with scripts

I am new to this forum and have not developed anything in FMP for a number of years. I have started an ambitious project.

I started an "Issues Tracking" project to build aworking prototype tracking / reporting system and get the users away from using Excel. I started with a FMPro Template.

We have an internal IT app that tracks projects. This system can export the data to a xls file. I have created a QA Main db that maps these fields so I can import the xls file.

There are 3 situations in the daily export: (1) dates changed in some records (there are 3 different dates for projects status: DatePushedtoQA, DateQAComplete, DateUATComplete), (2) records have been added and (3) records have been deleted.

The second DB is called QA_import for the daily file / updates. I built different scripts to do a lookup and replace the contents (for each of the "Date..." fields) if the date in the import file was greater than the date in the QA Main record.

How do I get the script to repeat so it searches all records in QA Main and replaces where the date is newer? How would I build a script to import new records but not all records? I don't care about deleting previous.

QA Main then feeds QA Tracking where the project is tracked within the Business Unit with calcualted average days and specific notes.

My next step is to build a script that when this QA Tracking is loaded, it looks up for any updated date info from QA Main. Is this a Portal situation wher the most recent information is always desired?

If I need to attach files, let me know.

Thanks!