用PB做的一个图书管理系统，是我在上课的过程中开发的，一切都实用，其中错误在老师的指导下修改，大家可以下载学习研究或参考！-PB to do with a library management system, is the process I developed in school, everything is useful, in which the error under the guidance of the teacher changes, you can download the st