What is ADO? - New Features
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ADO 2.5 and 2.6 have a host of new features that make programming easier and extend the goal of Universal Data Access. This section only summarizes them; I deal with them in more detail in later chapters.
ADO 2.5
The Record Object The Record object is designed to deal with Document Source Providers, which are OLE DB Providers that don’t access databases, but provide data from semistructured data stores. Two examples of this are Microsoft’s Exchange Server 2000 and Internet Information Server 5.0; both are sources of large amounts of data, and the OLE DB Provider for Internet Publishing allows you to access the data storage structure and the stored objects themselves.
The primary purpose of the Record object is to map a node in a tree-like structure of a document source. It works in conjunction with the Recordset but is not directly applicable to relational data sources.
The Stream Object The Stream object is a component that wraps the COM IStream interface, allowing easy access to streams of memory. This provides a way to transfer Recordsets directly to other components (such as the ASP 3.0 Request and Response objects) that support streams. The Stream is also used with Document Source Providers to allow access to file contents.
ADO 2.6
Command Streams Command streams allow a Stream object to be used as the source of a command. A good example of this is a Stream containing an XML command to be executed against SQL Server 2000.
Results in Streams Along with command streams, ADO 2.6 allows the results of a data query to be returned into a Stream object. This is particularly useful for obtaining XML data directly from SQL Server 2000.
Dialect Property This identifies the syntax rules the provider uses when parsing strings or streams. Its main use is for XML-generated recordsets, where the dialect identifies what form of XML the recordset is stored in.
Single Row Resultsets Because of the way ADO worked, singleton commands (commands that return only a single row) were always a performance hit, but ADO 2.6 has improved the performance of such commands.
Field Status Values The Status property of the Field object is now filled with information to help with the dreaded “Errors Occurred” error.
SQL Variant Support for Cursor Service Extended support for variant types has been added to the OLE DB Cursor Service.
ADOX Group and User Properties The Properties collection has been added to the ActiveX Data Objects Extensions (ADOX) Group and User properties to allow access to provider-specific properties.
ADO MD UniqueName support The UniqueName property can now be used to access ActiveX Data Objects Multidimensional ADO MD objects. This means that parent collections no longer need to be populated to retrieve schema objects.
ADO 2.7
ADO 2.7 didn’t introduce any new features; it simply provided support for 64-bit operating systems.
 This is from ADO Programmer's Reference, by Dave Sussman (Apress, ISBN 1590593421). Check it out at your favorite bookstore today. Buy this book now. |
Next: ADO 2.8 >>
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