This is something I just don’t remember, so I thought this would be a good place to post it. If you are trying to connect to a named instance of SQL Server, for example TECHKNOWSOLVETECHKNOWSOLVE2000, you might get an error in your code that says this server doesn’t exist. The quick and easy fix is to refer to the server by its port number, ie TECHKNOWSOLVE, 444. In this instance TECHKNOWSOLVE is the name of the server and the port number is 444. Note that the server name is followed by a comma, not the backslash that is used in named instances.
How do you find out what port number your named instance is using? In SQL Server 2000, use the Server Network Utility. Choose your named instance. Under “Enabled Protocols”, click on “TCP/IP”. Click on the “Properties” button. There you will see a number for “Default Port”. This is the number that will follow your server name.
I haven’t tried this with SQL Server 2005, but this article tells you how to find the port for SQL Server 2005 (and SQL Server 2000, for that matter.)
TechKnowSolve Blog 