Table Look Up

If I have a table called 'members':

   Member Number   First Name Last Name 

        562323               Fred          Smith

        678944               Jane          Jones

and I want to upload a CSV file into another table called 'books'

    Member Number           Book Title                    Borrowed Date         Returned

         562323              Tale of Two Cities                   01/01/2018             1

         562323              1984                                     17/02/2018             0

         678944              Romeo and Juliet                    19/03/2018             0

If I have to upload a CSV every week into 'books' how do I get the new records in 'books' to automatically link to the 'members' table so that members book borrowing status can be viewed?

Thanks