Beginning Visual Basic Database Programming
Size: 14.0 MB
All software is based on the principle of manipulating data. Whether it's the code that runs inside your
VCR to start recording at a specific time, or air traffic control software, code is always working with
data in one form or another.
Today, we find that sophisticated applications store their data in a "database", a central repository of
data overseen by a Database Management System, or DBMS. A DBMS does two things. Firstly, it
handles the storage of the data. Secondly, it provides mechanisms for retrieving data as well as adding,
removing, and changing data. A DBMS endeavors to do this in the most efficient way possible.
Over the years, the DBMS market has grown into a mature sophisticated industry in its own right, offering
products designed for use in large enterprise environments like Oracle 9i or Microsoft SQL Server 2000,
down to products designed for use on the desktop like Microsoft Access. In some cases, you even find that
software packages include their own DBMS software for managing their own proprietary databases.
You'll find in your work as a programmer that applications often require access to data managed by a
DBMS. In fact, you'll most likely find that using a DBMS is the easiest way to store and manipulate your
application's data. However, with a wide variety of vendors to choose from, how can we write
application code that can work with any database our customer cares to choose?
The trick here is to build your application to work with a "data access layer" of some kind. Rather than
writing code that specifically requires a specific DBMS, you write code that talks to the layer. It's then
the layer's responsibility to switch to the "native" calls that the DBMS itself uses. Microsoft calls this
vision "Universal Data Access", or UDA. Microsoft's latest tool for UDA is ADO.NET, a comprehensive
set of objects that work together to make up a data access layer.
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