Datasheet

ODBCDirect, a DAO add-on that routed the ODBC requests through RDO instead of the JET engine, the
performance gap between the two became much smaller. Finally, it wasn’t long after the release of RDO
that Microsoft’s next universal access API was released.
Figure 1-3
ADO
Microsoft introduced ActiveX Data Objects (ADO) primarily to provide a higher-level API for working
with OLE-DB. With this release, Microsoft took many of the lessons from the past to build a lighter,
more efficient, and more universal data access API. Unlike RDO, ADO was initially promoted as a
replacement for both DAO and RDO. At the time of its release, it (along with OLE-DB) was widely
believed to be a universal solution for accessing any type of data — from databases to e-mail, flat text
files, and spreadsheets.
ADO represented a major shift from previous methods of data access. With DAO and RDO, developers
were expected to navigate a tree of objects in order to build and execute queries. For example, to execute
a simple insert query in RDO, developers couldn’t just create an
rdoQuery object and execute it. Instead,
they first needed to create the
rdoEngine object, then the rdoEnvironment as a child of it, then an
rdoConnection, and finally the rdoQuery. It was a very similar situation with DAO. With ADO,
Non-
Access DB
Application
DAO
ODBC
JET Engine
MS Access
DB
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