From the book

Pricing > 20 pounds

2. Select the name of the publishing house and avg (pricing) as the average pricing.

From book publishing house

Where are the books? Publishing house number = publishing house. Press number

Group by publishing house number

3. Update SOB pricing =0.95* pricing.

Where (select pricing from books and press where books. Press number = press. Press number and name =' Science Press')

4. Select the title of the book, the name of the first author and the name of the publishing house.

From books, publishers, authors, books

Where are the books? Press no. = Press No. And books. Book number = book number. And the book number. = Author number. = author. Author number and authors rank = 1.