Data adapters are an integral part of the ADO.NET managed providers. They are the set of objects used to communicate between a data source and a DataSet. Adapters are used to exchange data between a data source and a DataSet. Mostly, this would mean reading data from a database into a DataSet, and then writing changed data from the DataSet back to the database. The DataAdapter, however, is more capable. It can move data between any source and a DataSet. For example, there could be an adapter that moves data between a Microsoft Exchange server and a DataSet.
Generally, we can configure the DataAdapter so that we can specify what data to move into and out of the DataSet. Often this takes the form of references to SQL statements or stored procedures that are invoked to read or write to a database. ADO.NET has two primary data adapters for use with databases:
- The OleDbDataAdapter: This object is suitable for use with any data source exposed by an OLEDB provider.
- The SqlDataAdapter: The SQLDataAdapter object is specific to SQL Server. Because it does not have to go through an OLEDB layer, it is faster than the OleDbDataAdapter. However, it can only be used with SQL Server 7.0 or later.
This means that vendors can create vendor specific DataAdapters that can be faster or more efficient for different types of data sources. Normally, one DataAdapter is created for one table or data set. If the DataSet consists of more than one table, usually a separate DataAdapter is created for each table. For populating a DataSet, a DataAdapter's Fill method is called. For writing the updated data back to the table, the DataAdapter's update method is called. A DataAdapter is created by the DataAdapter configuration wizard or by using the server explorer. A DataAdapter can also be configured manually by using the property window.
