如何在MYSQL中使用select查询？

I want to print a table of books(in library management) which are issued 14 days ago. The mysql query $query ="select * from issue"; I am using is not proper. Please tell me how to use this query over here..

use SUM

SELECT SUM(no_of_copies) AS totalBooks FROM tablename

or Group by sum

SELECT SUM(no_of_copies) AS totalBooks FROM tablename group by BookName