How to copy currently working mdf file using C#

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C#

I want to copy the mdf file and this mdf file is currently Used in my application. when i am trying to copy mdf file then it will display error currenly file used in other process i have tried to dispose the connection but this also not helpful for me please help me.

What I have tried:

//Here i am Disconnecting the SQL connection
connection.Close();
SqlConnection.ClearPool(connection);
connection.Dispose();
connection.Dispose();

//Here i am trying to copy but not success
System.IO.File.Copy(DownloadmdfPath, UploadmdfPath, true);