Visual C++ 6 Unleashed

By MICKEY WILLIAMS and David Bennett

• Table of Contents
  • Copyright
  • About the Authors
  • About the Contributors
  • Acknowledgments
  • Tell Us What You Think!
  • Introduction
  • How to Use This Book
  • What You Need to Use This Book
  • What's New in Visual C++ 6.0
  • Contacting the Main Author
  • Part I: Introduction
  • Chapter 1. The Visual C++ 6.0 Environment
  • Part II: MFC Programming
  • Chapter 2. MFC Class Library Overview
  • Chapter 3. MFC Message Handling Mechanism
  • Chapter 4. The Document View Architecture
  • Chapter 5. Creating and Using Dialog Boxes
  • Chapter 6. Working with Device Contexts and GDI Objects
  • Chapter 7. Creating and Using Property Sheets
  • Chapter 8. Working with the File System
  • Chapter 9. Using Serialization with File and Archive Objects
  • Part III: Internet Programming with MFC
  • Chapter 10. MFC and the Internet Server API (ISAPI)
  • Chapter 11. The WinInet API
  • Chapter 12. MFC HTML Support
  • Part IV: Advanced Programming Topics
  • Chapter 13. Using the Standard C++ Library
  • Chapter 14. Error Detection and Exception Handling Techniques
  • Chapter 15. Debugging and Profiling Strategies
  • Chapter 16. Multithreading
  • Chapter 17. Using Scripting and Other Tools to Automate the Visual C++ IDE
  • Part V: Database Programming
  • Chapter 18. Creating Custom AppWizards
  • Chapter 19. Database Overview
  • Chapter 20. ODBC Programming
  • Chapter 21. MFC Database Classes
  • Chapter 22. Using OLE DB
  • Chapter 23. Programming with ADO
    • ADO Objects
    • Connection Objects
    • ADOCommand Objects
    • ADORecordset Objects
    • ADOFields Collections and ADOField Objects
    • ADOParameter Objects and the ADOParameters Collection
    • ADOProperty Objects and ADOProperties Collections
    • Writing a Visual C++ ADO Application
    • Processing ADO Errors
    • Enhanced ADO Recordset Functionality
    • Executing Commands
    • Transactions
    • Summary
  • Part VI: MFC Support for COM and ActiveX
  • Chapter 24. Overview of COM and Active Technologies
  • Chapter 25. Active Documents
  • Chapter 26. Active Containers
  • Chapter 27. Active Servers
  • Chapter 28. ActiveX Controls
  • Part VII: Using the Active Template Library
  • Chapter 29. ATL Architecture
  • Chapter 30. Creating COM Objects Using ATL
  • Chapter 31. Creating ActiveX Controls Using ATL
  • Chapter 32. Using ATL to Create MTS and COM+ Components
  • Part VIII: Finishing Touches
  • Chapter 33. Adding Windows Help
  • Part IX: Appendix

ADOParameter Objects and the ADOParameters Collection

ADOCommand objects contain an ADOParameters collection, which contains all the parameters associated with the command. Each of the individual ADOParameter objects is used to contain information about a parameter that is passed into the command text at runtime, or returned from a procedure executed in a command. New ADOParameter objects are created with the CreateParameter() method of a ADOCommand object.

ADOParameters Collection Members

The ADOParameters collection includes a Count property, which gives the number of individual Parameter objects in the collection, and an Item property, which is used to retrieve individual ADOParameter objects. You can add new ADOParameter objects to the collection with the Append() method or delete them from the collection with the Delete() method. In addition, the Refresh() method can be used to gather information from the provider about parameters used in procedures or parameterized commands.

ADOParameter Object Properties

Each of the ADOParameter objects in the ADOParameters collection of a command has the following properties, although some properties might not be available for certain providers:

• Attributes contains a combination of several bit flags that indicate whether the parameter accepts signed, nullable, and/or long data values.
• Direction indicates whether the parameter is used for input, output, or both.
• Name contains the name of the parameter.
• NumericScale is used to determine the number of places to the right of the decimal that are used for numeric parameters.
• Precision indicates the total number of digits used to represent a value for the parameter.
• Size contains the maximum size of the parameter value in bytes or characters.
• Type specifies the data type for the parameter's value.
• Value contains the actual value assigned to the parameter.

ADOParameter Object Methods

The only method provided by ADOParameter objects is AppendChunk(), which is used to append data to large text or binary parameter values.

Share This