How does walmart gather data information and how is it applied towards their business success?

I need to know how One Company (walmart) uses a good marketing information system to gather date. How is the information gather, the type of information gather, and how that information helps the company market its products.|||In only one, simple example, the company may review sales from the registers to determine which products sell best of worst during certain days, and at which locations. In that way, inventory can be distributed in such a way that the stores not selling as much of a product won't have to store as much on their shelves and, at other stores where the demand is greater, can keep more stock on hand.





Remember, any stock on the shelf is money spent and not returning a profit. Money can only be made by moving stock off of the shelf and into the customer's carts.