More DSN Trivia!

I’ve gathered a few more interesting bits of
information about DSN’s that I’d like to share with you this week:

  • From Swynk reader Rod Burke: Basically,
    if you set the system dsn (not file dsn, and I haven’t tried user dsn)
    to be non-trusted, this property is ignored when the DSN is used later.
    Seems to apply only to applications which pop up a login dialog …
    i.e. not those which supply a username/password in the connection
    string or similar. If you expect Access, for example, to present a
    dialog for username password on a non-trusted connection to SQL
    Server, it will first complain about the trusted connection attempt
    failing. It’s documented at http://support.microsoft.com/support/kb/articles/Q279/5/26.asp.
    (Added Feb 15, 2001)
  • From Swynk reader and good friend Matt
    Owen: You might want to consider specifying a complete path to your
    file DSN’s. By providing the path you don’t have to check that someone
    has changed the default folder. You can just use the application
    folder where your executable is stored, or keep your DSN’s in a file
    share with a fully qualified UNC.
  • Simon Clark wrote to mention that using
    a DSN or UDL could possibly degrade performance if you open and close
    a connection a lot – due to the disk/registry reads involved to get
    the connection info. I can see in some situations that it would make
    sense to cache the connection information to save hitting the disk
    over and over, a perfect use for a dsnless connection where you load
    the connect string at startup and use it for the entire session.
    Overall I still prefer UDL’s as they are more easily maintained.
  • Did you know that you can have a File
    DSN that points to a System DSN? Why would you want to? As best I can
    tell from researching MSDN this was a fix for MS Query, which in it’s
    earlier versions could only see File DSN’s. It’s pretty simple, just
    one line: [ODBC]DSN=SystemDSNName. PLEASE try not to find a use for
    this one!
  • That the version of MS Query shipped as
    part of Office 2000 supports DSN’s, but I can’t find a way to get it
    to use a UDL or a connection string? It does support OLAP cubes, so I
    guess it’s not all bad!
  • I’ve posted an update to my DSNGen
    utility. Allan Mitchell reported the first (and only so far!)
    bug  – while creating a file DSN, if the server name was
    "(local)" and the user selected the ServerName as Prefix
    option, the resulting DSN would not show up in the ODBC applet (the
    DSN would be created as (LOCAL)_dbname.DSN). If you haven’t done so
    already, take a look at it. 

If you’re new to DSN’s, take a look at my
previous articles DSN’s – What are they?, DSN,
DSN-Less, or UDL?
, and DSNGen – Another Tool for the
Toolbox.
If you’ve got another tip or comment about DSN’s or UDL’s, please
email me. 

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