Create a functional Customer Database in Excel -- 2

The objective of this project is to create a customer database for a business that distributes construction materials. The customer database will include existing customers (see attached file, "Existing Customers_9.18.19") and potential new customers (see attached file, "Detail20191007071000"). For each customer or potential new customer, the database will include key identifying information including: Customer Name, Customer #, Existing Customer / Potential New Customer, Zip Code, Employee Count, Sales Volume, Primary SIC Code, Primary NAICS Code...potentially others. The database should be made such that it is easy to filter based on any piece of the aforementioned "key identifying information." An initial step for this project will be to map the "Existing Customers_9.18.19" file to the "Detail20191007071000" file such that there are no duplicates in the ultimate customer database and it is evident which are existing customers and which are potential new customers.