substring query

[Aaron Savage]

I am looking for some guidance on creating a substring query.  I have
a column that stores a path to a file.  I would like to extract that
file extension and that is it and display it on my results.  However,
the paths are different lengths and some extensions are 3 letter and
some are 4, eq 'html'.  The only common they all have is the period
before the extension.  Anyone created a nested substring query that
can do what I am looking to do?

Thanks,
Aaron