-- 25 --
CREATE VIEW q25 AS
SELECT    invoice.C_code, COUNT(DISTINCT invoice.I_code) AS 'Number of Invoice',
          SUM(L_units * L_price) AS 'Total Customer Purchases'
FROM      invoice, line
WHERE     invoice.I_code = line.I_code
GROUP BY  invoice.C_code;

-- 26 --
CREATE VIEW q26 AS
SELECT    COUNT('Invoice Total') AS 'Total Invoices', 
          SUM('Total Customer Purchases') AS 'Total Sales',
          MIN('Total Customer Purchases') AS 'Minimum Purchase', 
          MAX('Total Customer Purchases') AS 'Largest Purchase'
FROM      q25, invoice, line
WHERE     invoice.I_code = line.I_code
GROUP BY  invoice.C_code;