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Preparing and Executing Commands

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Commands are instructions issued to a provider to perform some operations against the underlying data source. An SQL statement, for example, is a command to the Microsoft SQL Data Provider. In ADO, commands are typically represented by Command objects, although simple commands can also be issued through Connection or Recordset objects.

You can use the Command object to request any supported type of operation from the provider, assuming that the provider can interpret the command string properly. A common operation for data providers is to query a database and return records in a Recordset object, which that can be thought of as a container to hold the result and a tool to view the result. As with many ADO objects, some Command object collections, methods, or properties might generate errors when referenced, depending on the functionality of the provider.

In addition to using Command objects, you can use the Execute method on the Connection object or the Open method on the Recordset object to issue a command and have it executed. However, you should use a Command object if you need to reuse a command in your code, or if you need to pass detailed parameter information with your command. These scenarios are covered in more detail later in this section.

Note

Certain Commands can return a result set as a binary stream or as a single Record rather than as a Recordset, if this is supported by the provider. Also, some Commands are not intended to return any result set at all (for example, a SQL Update query). This section will cover the most typical scenario, however: executing Commands that return results as a Recordset object. For more information about returning results into Records or Streams, see Records and Streams.

This section contains the following topics.