Checkout the mysql WITH ROLLUP
UPDATE
After reading your quesion again it might be as simple as adding GROUP BY books.book_id
SELECT books.book_id, url, title, short_desc, img, featured, SUM(views) as total_views
FROM books,book_category,book_click WHERE enable=1 AND category_id=7
AND books.book_id=book_category.book_id
ORDER BY strong texttotal_views DESC GROUP BY books.book_id
Original Answer:
http://dev.mysql.com/doc/refman/5.1/en/group-by-modifiers.html
SELECT books.book_id, url, title, short_desc, img, featured, SUM(views) as total_views
FROM books,book_category,book_click WHERE enable=1 AND category_id=7
AND books.book_id=book_category.book_id
ORDER BY strong texttotal_views DESC GROUP BY your_grouping WITH ROLLUP;
Example
mysql> SELECT year, country, product, SUM(profit)
-> FROM sales
-> GROUP BY year, country, product WITH ROLLUP;
+------+---------+------------+-------------+
| year | country | product | SUM(profit) |
+------+---------+------------+-------------+
| 2000 | Finland | Computer | 1500 |
| 2000 | Finland | Phone | 100 |
| 2000 | Finland | NULL | 1600 |
| 2000 | India | Calculator | 150 |
| 2000 | India | Computer | 1200 |
| 2000 | India | NULL | 1350 |