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ASP ADVANCED

This chapter introduces the ActiveX Data Objects (ADO).  The first section provides an overview of these objects.  The second section gives you a step-by-step guide to using the ADO to retrieve and store data in a database.  Finally, in the third section, you are formally introduced to a particularly important ADO object: the connection object.

Using the ActiveX Data Objects (ADO), you can store and retrieve data from a variety of data providers.  For example, you can use the ADO to access information from Microsoft Access and the Microsoft SQL and Oracle database servers, You can even use the ADO to retrieve information from a Microsoft Excel spreadsheet.

In this book, you learn how to use the ADO with Microsoft SQL Server.  All the examples assume that this database is being used.  However, you should realize that much of what you learn in the following chapters is transferable to other databases as well.

In Part III, "Working with Data: SQL," you learned how to use Structured Query Language (SQL).  Starting with this chapter, you put this knowledge to good use.  The emphasis is on using SQL with the ADO to store and retrieve data from a database.  This combination of the ADO and SQL is powerful.

The ActiveX Data Objects consists of seven independent objects. The following list names these objects and provides a brief explanation of their functions:

• Connection object.  Represents a unique session with a data source.  For example, you can use the Connection object to open a connection to Microsoft SQL Server.
• Recordset object.  Represents records from a data provider.  For example, you can use the Recordset object to alter the records contained in a SQL Server table.
• Field object. Represents an individual field in a Recordset.
• command object. Represents a command.  For example, you can use the Command object to execute a SQL stored procedure or a parameterized query.
• Parameter object.  Represents an individual parameter in a SQL stored procedure or parameterized query.
• Property object. Represents data-provider-specific properties.
• Error object. Represents ADO errors.

When using the ADO, you'll be most directly interacting with the connection,Recordset, and Command objects.  This chapter provides a detailed overview of the Connection object.  In the next two chapters, you learn how to use both the Recordset and Command objects.  First, however, you must learn how to configure your server to use the ADO.