Understanding all the variants of the FOR command would be quite an achievement and I hope you started by reading the documentation
http://technet.microsoft.com/en-us/library/bb490909.aspx[
^].
To have the filename treated as a command and have it's standard output parsed, you will need to add the usebackq option to your parsing keywords and back quote the filename.
for /F "usebackq delims=" %%a in (`C:\Users\u316383\Documents\Backup\ConsoleApplication3.exe`) do set datayyyymmdd=%%a.
If the filename contains spaces then use back quotes and double quotes.
for /F "usebackq delims=" %%a in (`"C:\Users\u316383\Documents\Backup Files\ConsoleApplication3.exe"`) do set datayyyymmdd=%%a.
Alan.