How to read all the records of mnesia database in erlang?

I ma new in erlang and I need to do some operations for all records I get from mnesia database.

Result = mnesia:dirty_read(mydatabase, {key1, key2}),
        case Result of 
            [] ->
                ?DEBUG("No such record found", []);
            [#mydatabase{key3 = Key3}] ->
                %% some operations
        end

How can I add a loop to my code that execute some operations for all records?

I am not even sure if the code above does it or not?