This article shows a better way to import and link CSV files into a Google spreadsheet. By using a simple technique you can protect your spreadsheet and safely query data from an external CSV even when the structure of the CSV files changes.
A better use of lookup(), vlookup(), and hlookup() with examples for Google Sheets
There is a better way to use Google Sheets lookup() functions With a few simple examples you will learn how to hide your data (hash tables) and use the functions in a more advanced yet simple way.