我无法在App_data(vs 2010 visual studio)中添加.mdf文件。 如果我在APP_DATA点击右键并尝试添加现有项目并选择mydatabase.mdf并单击OK我收到此错误:将.mdf文件打开到app_data时出错
The file can not be opened because it is used by another process.Please close all applications that might access this file and try again.
但我只是运行Visual Studio。