Sql-server – Installing sqlserver2008 SP1, the ‘select features’ is empty

An nvarchar column can store any Unicode data. A varchar column is restricted to an 8-bit codepage. Some people think that varchar should be used because it takes up less space. I believe this is not the correct answer. Codepage incompatabilities are a pain, and Unicode is the cure for codepage problems. With cheap disk and memory nowadays, there is really no reason to waste time mucking around with code pages anymore.

All modern operating systems and development platforms use Unicode internally. By using nvarchar rather than varchar, you can avoid doing encoding conversions every time you read from or write to the database. Conversions take time, and are prone to errors. And recovery from conversion errors is a non-trivial problem.

If you are interfacing with an application that uses only ASCII, I would still recommend using Unicode in the database. The OS and database collation algorithms will work better with Unicode. Unicode avoids conversion problems when interfacing with other systems. And you will be preparing for the future. And you can always validate that your data is restricted to 7-bit ASCII for whatever legacy system you're having to maintain, even while enjoying some of the benefits of full Unicode storage.

My guess is that your DLL files are release build, and so the JIT compiler is optimising away some of the function calls (it often inlines small functions). That means that when the runtime tries to translate from the jitted code back to the PDB, it gets confused.

Try adding an .ini file to your application root; so if your app is prog.exe, add prog.ini with the following content;

[.NET Framework Debugging Control] 
GenerateTrackingInfo=1
AllowOptimize=0

This will stop the JIT compiler from optimising away the calls, and let your PDB files refer to the correct calls in your code. You'll need to restart the application, and because it's running without optimisations, it'll slow it down to DEBUG build levels, but you should be able to attach the debugger correctly.