Problem
1. Write an SQL statement to show the sum of SubTotal (this is the money earned by HSD on products sold exclusive of shipping costs and taxes) for INVOICE as SumOfSubTotal.
2. Write an SQL statement to show the average of Subtotal (this is the money earned by HSD on products sold exclusive of shipping costs and taxes) for INVOICE as AverageOfSubTotal.
3. Write an SQL statement to show both the sum and the average of Subtotal (this is the money earned by HSD on products sold exclusive of shipping costs and taxes) for INVOICE as SumOfSubTotal and AverageOfSubTotal respectively.
The response should include a reference list. Double-space, using Times New Roman 12 pnt font, one-inch margins, and APA style of writing and citations.