Given XLSX (INNER JOIN of three tables) and an empty database. How to pour one into the other?

Question

SQL

Task: to fill in XLSX (INNER JOIN of three tables) in a DB, correctly putting down sheaves.
Initially, the database is empty, there is only a structure without data.
What is the best way to do this?
The task is one-time, so I don't want to write complex tools.
Piece number two. We manually created an “empty store” in the database, and its ID will have to be written in all lines when uploading data. What to do with this?