Modify data before making a relation

Hi,

I am really new to Power BI and it seems really promising!

I would like to make a relationship between two fields which are in fact Serial Numbers :

- First is in a sqlite DB and is of type AA0000

- Second is in a Excel file and is of type AA0000-X

To be able to make the link between both, I would like Power BI to ignore the last two caracters coming from the Excel file that are in fact useless.

Any idea how to deal with it?

I would like as much as possible not to modify the Excel file since these are raw data extracted from another SAP DB periodicaly. It contains only text, no formulae. Otherwhise, I would have just put =LEFT(...;6) in the excel file.

Thanks a lot,

Max