identify all non-prime attributes in the table 

Name: (28 pts.) The table below stored customer invoices. Each customer has a unique customer# and may have multiple invoices. Each invoice has a unique invoice number and may have one or multiple invoice lines. Each invoice line is for only one product. For example, the customer #9870 (Winston) in the table below has two invoices, #105 and #260. The invoice #105 contained two invoice lines, each of which is for a different product. Those attributes are self- explanatory. Note that the sample data in the table below are only for illustration limited by the space. Customer# 9870 9870 7840 9870 Name Winston Winston Harris Winston *** Mobile Invoice# 123-221-3344 105 123-221-3344 105 721-531-5133 210 123-221-3344 260 ... InvoiceDate InvoiceLine# ProductNum 2/10/2013 1 3412-CH 2/10/2013 2 5623-WR 2/12/2013 1 3412-CH 3/15/2013 1 2311-SQ Product Desc Claw Hammer B&D jigsaw Claw Hammer PVC pipe ... Unit 20 5 15 40 ... UnitPrice 25.00 120.00 25.00 6.500 *** ease answer the following questions. (Note that each question consists of two parts. Make sure you give complete wers. You may state your assumptions to clarify ambiguities or missing information but do not change and tradict to the given table.) (a) Identify all candidate key(s) of the table and explain why it (they) is (are) qualified to be the candidate key and choose the primary key for the table (3 pts.)