如何从代码中设置Sql Server中的默认数据库？

I can't seem to figure out how to set the default database in Sql Server from code. This can be either .Net code or T-Sql (T-Sql would be nice since it would be easy to use in any language). I searched Google and could only find how to do it in Sql Server Management Studio.I can't seem to figure out how to set the defau