Browsing for ODBC Data Source Names (DSN)

Environment: VC6 SP4, NT4 SP5

Introduction

This article is the result of some work I did in a recent project. I was
improving a configuration program user interface for a complex client-server
application where several databases where used. A common configuration option
was what DSN (Data Source Name) to use. Since users had found it inconvenient
to look the DSN name up using the ODBC configuration tool in the control panel
and then type the name manually, we had decided to add a browse for DSN button.

Since I didn’t find any standard “browse for DSN dialog” I wrapped the
interesting calls to the ODBC API in a simple class called
CDSNCollection which then was used to enumerate the DSNs and show them
in a home made browse dialog.

The pitfalls

Doing simple things with ODBC API in C++ can easily become complicated. First of
all an environment handle has to be created (see CDSNCollection::CDSNCollection
for details
). Then one must specify which ODBC version to use (see
CDSNCollection::CDSNCollection for details
). This might seam strange since the
latest version probably is used 99% of the time. My guess is that
Microsoft has chosen this approach in order to achieve forward capability even
when making major changes in the ODBC API. And when you think of it for a while
it actually makes more sense than the “classical” Microsoft way to achieve backward
and forward capability.

A few thoughts

I don’t usually use C++ for heavy database action and this operation is quite simple
since it does not use any specific database. Still two calls are needed just
to initialize before the simple task of getting a few DSN names. Error handling is
also a little special; see the call to SQLGetDiagRec in
CDSNCollection::CallSQLDataSources.

Since I just created a simple class which just wraps a simple ODBC API call (initialization
and error handling does not really count… 🙂 there is not much more to say. Just use
it if you want to enumerate through your DSNs…

Downloads

Download demo project – 17 Kb

Download source – 3 Kb

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