实现增删该查的封装，看测试例子就可以了，可以把表里面的内容放入链表，因为只是数据库模块，所以节点没有free(),使用时注意。-The investigation of the package to achieve deletions, see test case on it, you can put the table inside the content into the list, because it is only the　module, the node does not free (), when using the attention.