数据访问框架.用于选择不同数据源的操作.包含了所有的ADO.NET的操作.不知道怎么传多个文件.所以只传了一个文件.第一次来-Data access framework. Used to select a different data source operation. Contains all of the ADO.NET operation. Do not know how to mass multiple files. Therefore of only passing on a doc