Hi @Aditi_Mehta
For Pega DB queries, you may want to try the pyRetrieveReportDataExtension activity (v25 onwards) which executes for every report definition call with proper conditions of the report name, view which this call came from, etc and then you can log/audit the entries as per your requirement. Not sure if other community members have any better ideas.
For search and select tables hitting external systems via Connect-Rest, you can check the below post. Although i have not tried this myself.
Hope this helps.
Regards
JC