2. Write a SELECT statement that returns two columns: VendorName and
PaymentSum, where PaymentSum is the sum of the PaymentTotal column. Group
the result set by VendorName. Return only 10 rows, corresponding to the 10 vendors
who’ve been paid the most.
Hint: Use the TOP clause and join Vendors to Invoices.

3. Write a SELECT statement that returns three columns: VendorName, InvoiceCount,
and InvoiceSum. InvoiceCount is the count of the number of invoices, and
InvoiceSum is the sum of the InvoiceTotal column. Group the result set by vendor.
Sort the result set so that the vendor with the highest number of invoices appears
first.

4. Write a SELECT statement that returns three columns: AccountDescription,
LineItemCount, and LineItemSum. LineItemCount is the number of entries in the
InvoiceLineItems table that have that AccountNo. LineItemSum is the sum of the
InvoiceLineItemAmount column for that AccountNo. Filter the result set to include
only those rows with LineItemCount greater than 1. Group the result set by account
description, and sort it by descending LineItemCount.
Hint: Join the GLAccounts table to the InvoiceLineItems table.

5. Modify the solution to exercise 4 to filter for invoices dated in the first quarter of
2002 (January 1, 2002 to March 31, 2002).
Hint: Join to the Invoices table to code a search condition based on InvoiceDate.

6. Write a SELECT statement that answers the following question: What is the total
amount invoiced for each AccountNo? Use the WITH ROLLUP operator to include
a row that gives the grand total.
Hint: Use the InvoiceLineItemAmount column of the InvoiceLineItems table.

7. Write a SELECT statement that returns four columns: VendorName,
AccountDescription, LineItemCount, and LineItemSum. LineItemCount is the row
count, and LineItemSum is the sum of the InvoiceLineItemAmount column. For each
vendor and account, return the number and sum of line items, sorted first by vendor,
then by account description.
Hint: Use a four-way join.

8. Write a SELECT statement that answers this question: Which vendors are being paid
from more than one account? Return two columns: the vendor name and the total
number of accounts that apply to that vendor’s invoices.