PROBLEM SOLVED (or at least circumvented).

I got access to a different database -- a full SQL Server 2008 database. I changed my connection string to point at that database, then tried connecting first from my standalone application (success) and then from within Unity (success!).

I don't know specifically why I couldn't connect to my local SQL Server Express database, but presumably it was for one of the following reasons.

• Unity might not work with SQL Server Express.
• Unity might not work with Windows Authentication (I used SQL Server Authentication to connect to the Amazon-hosted server).
• There could be something about my local environment which prevents Unity from connecting to my database.

So I never did really solved the issue of connecting to my local database. However, ultimately we just need to connect to our customer's database and now I'm fairly confident that that can be done.

BTW, it seems to work fine with the default System.Data assembly -- I didn't have any System.Data.dll in my Unity project hierarchy. Here's the line from the Console log file.

• Platform assembly: C:Program Files (x86)Unity3.1EditorDataMonolibmono2.0System.Data.dll (this message is harmless)

This was all done with Unity 3.3.0f4.

Barry

This was helped to me: http://support.microsoft.com/kb/265808

I used Tcpview.exe to monitor network activity and found out a bit more about what is (and isn't) going on.

The bottom line is that I can't get Unity to attempt a TCP/IP connection at all -- at least, it doesn't get far enough to actually show anything in Tcpview. It does show a brief "SYN_SENT" packet when I hit "Play", but it does that regardless of the Unity application (even Bootcamp sends that :-)).

My Mono app works because it apparently uses Shared Memory -- it succeeds without showing anything in Tcpview. Based on that theory, I tried a few different URLs -- the following were all successful from my standalone application.

o "Server=string\sqlexpress;Database=AmksPhaseII;Integrated Security=SSPI;User ID=stringbarry;" o "Server=lpc:string\sqlexpress;Database=AmksPhaseII;Integrated Security=SSPI;User ID=stringbarry;" o "Server=tcp:string\sqlexpress,58649;Database=AmksPhaseII;Integrated Security=SSPI;User ID=stringbarry;" o "Server=string\sqlexpress,58649;Database=AmksPhaseII;Integrated Security=SSPI;User ID=stringbarry;"

The last two did force the application to use TCP/IP -- I could see it in Tcpview.

Unfortunately, they (and other connection strings) all failed when I tried them from within Unity. My best (and only) guess at this point is that perhaps Unity doesn't understand database instances (and hence doesn't understand the "sqlexpress" part of the connection string), but I think that's a long shot.

Any ideas from anyone???

Thanks, Barry

P.S. It turns out that the fields available for Mono applications are just a subset of those available for .NET, so I went ahead and built a .NET app using my library instead of a Mono app. I'm still using the exact same code in Unity, but with Unity's Mono environment, of course.

I would like to update this page to reflect my findings on this subject. Like Barry I also had the same troubles connecting to a local instance of SQL Express. After reading Barry's report I realized the trouble is in the named instance.

If you install SQL Express as a Default Instance (meaning the named instance is MSSQLSERVER) then you can get around this problem. It seems that Unity cannot deal with the named portion of the connection string. This is a special instance in SQL Server Express that allows you to connect via Data Source=localhost with no name.

Hi Tom,

Thank you! Seems like a great suggestion. I tried it, however, and am still getting the same error message.

The DLL I created to access the database this time was a standard .NET DLL (i.e., as opposed to a Mono version) -- i.e., I compiled it with Visual Studio 2010, which presumably uses the .NET version of System.Data, etc. As before (but this time in VS2010 instead of MonoDevelop, and using a standard .NET connection string instead of the Mono version), I can connect using my library if I run it from a small standalone test program, but loading that same library into Unity and calling it from there (via a small script attached to an empty object) results in failure:

Exception: An existing connection was forcibly closed by the remote host.

In short... no luck yet.

Thanks, Barry