宾馆客房管理系统外文毕业论文.docVIP

宾馆客房管理系统外文毕业论文 Architectural Overview of ADO.NET The ADO.NET object model consists of two fundamental components: the DataSet, which is disconnected from the data source and doesnt need to know where the data it h- olds came from; and the .NET data provider. The .NET data providers allow us to conn- ect to the data source, and to execute SQL commands against it. .NET Data Providers At the time of writing, there are three .NET data providers available: for SQL Server, for OLE DB data sources, and for ODBC-compliant data sources. Each provider exists in a namespace within the System.Data namespace, and consists of a number of classes. W- ell look at each of these providers shortly. Data Provider Components Each .NET data provider consists of four main components: Connection – used to connect to the data source Command – used to execute a command against the data source and retrieve a DataReader or DataSet, or to execute an INSERT, UPDATE, or DELETE command against the data source DataReader – a forward-only, read-only connected resultset DataAdapter – used to populate a DataSet with data from the data source, and to up- date the data source Note that these components are implemented separately by the .NET providers; ther- e isnt a single Connection class, for example. Instead, the SQL Server and OLE DB pro- viders implement SqlConnection and OleDbConnection classes respectively. These class- es derive directly from System.ComponentModel.Component – there isnt an abstract Co- nnection class – but they implement the same IDbConnection interface (in the System.D- ata namespace). The Connection Classes The connection classes are very similar to the ADO Connection object, and like that, they are used to represent a connection to a specific data source. The connection classes store the information that ADO.NET needs to connect to a data source in the form of a f- amiliar connection string (just as in ADO). The IDbConnection interfaces ConnectionS- tring property holds infor