1、该系统只是测试一下本人帮老师设计的类库是否正确。 2、只包含一些简单的查询(主键，条件，无条件)，添加，删除，修改。-1, the system just to test my class library designed to help the teacher is correct. 2, contains only some simple query (primary key, conditions, unconditional), add, delete, modify.