The schemas for the 2 tables are: Customers (20M rows)
  • CustomerID INT
  • Name VARCHAR (100)
  • Item VARCHAR (100)
  • Phone VARCHAR (15)
Purchases (20M rows)
  • PurchaseID INT
  • CustomerID INT
  • PurchaseDate DATE
  • AreaCode VARCHAR (3)
  • Item VARCHAR (100)
  • Price DECIMAL(10, 2)