MySqlConnection: 连接MySQL服务器数据库。
MySqlCommand:执行一条sql语句。
MySqlDataReader: 包含sql语句执行的结果，并提供一个方法从结果中阅读一行。
MySqlTransaction: 代表一个SQL事务在一个MySQL数据库。
MySqlException: MySQL报错时返回的Exception。
MySqlCommandBuilder: Automatically generates single-table commands used to reconcile changes made to a DataSet with the associated MySQL database.
MySqlDataAdapter: Represents a set of data commands and a database connection that are used to fill a data set and update a MySQL database.
MySqlHelper: Helper class that makes it easier to work with the provider.
