From: Rosa Almeida, warehouse manager at Juniper Lane
Re: This week's reorder list
Every Monday I decide what to reorder. An item needs reordering when the stock on hand won't last until a new delivery arrives: when its days of cover (stock divided by average daily sales) are fewer than the supplier's lead time in days.
Use the last 28 days of sales for the average. inventory.csv has stock and lead time per SKU; item_sales.csv has units sold per SKU per day, but only for days when the item sold at least one unit.
I need the list of products to reorder, and how many units of each to order.
Small details decide this list: a sales log with no rows for zero days, items that sold nothing at all, an item with no stock, and a retired SKU that still turns up in the sales feed. Each one changes the answer if handled the wrong way.