The HW$2$ Start File contains data imported into Excel from Microsoft$$s Northwind database. There are worksheets for the company$$s customers, products, product categories, and transactions. Each transaction is for a product purchased by a customer, but when a customer purchases multiple products at the same time, there are several corresponding rows in the Transactions table, one for each product purchased.

$1.$ The ID columns $($the first four columns$)$ allow you to look up names of customers, products, and product categories. However, some of the IDs in the Transactions may have error. There are three types of errors.

a$.$ First, an ID in the Transactions sheet might not correspond to any customer, product, or product category.

b$.$ Second, because each order is by a single customer, a given OrderID should correspond to only one CustomerID, but there may be some OrderIDs that have two or more CustomerIDs associated with them.

c$.$ Third, a given product ID should always correspond to the same product CategoryID, but there may be some productIDs that are associated with more than one CategoryID.

$2.$ Besides the corrupted IDs, there is one other potential type of error, concerning dates. Shipping dates can be blank $($for orders that haven$$t yet shipped$),$ but they shouldn$$t be before the corresponding order dates.