Carbon Data lets you visually combine and transform data from multiple CSVs, Excel Spreadsheets, and MySQL data sources (even behind VPNs), and do so repeatedly even when the source data is updated.
You can upload multiple spreadsheets simultaneously into Carbon Data, and import (read-only) data from MySQL databases, even if they're behind a VPN. You can then visually join these data sources together by providing a specific comparison column, to create a master table that's always up-to-date.