说明：  1.基于图书馆管理系统的mysql语句的基本增删查改范例 2.调用和创建存储过程基本例子 3.调用游标和多表连接范例 4.实现数据库备份范例
(1. the basic additions and deletions of MySQL statements based on library management system. 2. call and create a basic example of the stored procedure 3. invocation of cursor and multiple table connection examples 4. implementation of database backup examples)