Microsoft® Visual C#® .NET 2003 Unleashed

Implementing a Custom Command

When you think about implementing a custom data provider, you should usually start your thinking at the command level. The command is the workhorse of the entire provider. When a DataAdapter fills a DataSet, it uses a command to generate a DataReader that is then used to populate the DataSet. The command utilizes the existing connection to perform the actual data operation, including sending parameters, obtaining results, and populating output parameters.

The IDbCommand Interface

The IDbCommand interface defines the properties and methods listed in Table 28.4.

Table 28.4. Properties and Methods of the IDbCommand Interface

Property or Method	Description
CommandText	The text of the command. In most implementations, this ...