VS2010在创建C++项目时提示无法创建sdf文件，可能是没有安装SQL Server Compact 3.5 或该文件无法被访问。

具体的提示如下：

An error occurred while creating or opening the C++ browsing database file r:/t1/t1.sdf. IntelliSense and browsing information will not be available for C++ projects.

Ensure that Microsoft SQL Server Compact 3.5 is installed and that no other applications are accessing the file. If this problem persists, delete the file and reopen the solution.

SSCERuntime-CHS-X86.msi

解决方案：
去下载安装Microsoft SQL Server Compact 3.5 Service Pack 2 for Windows Desktop，下载地址：http://www.microsoft.com/en-us/download/details.aspx?id=5783