Filtering a table using another table

I have a table (call it the master table) using MySQL. What I have to do
is first to select a few records and then to have the selection to be
save on a floppy diskette. Since the master table has a lot of
information so I decide to only store the unique record id of the master
table. Currently I use a TClientDataset to create a single filed table
(call it the selection table) to store the selection and save it to a
file. Later I can use the selection table to filter the master table -
just showing the records that has their id stored in the slection table.

My problem is when I want to filter the master table using the selection
table - I don't know how to do it since the selection table is not part
of the MySWL table. I don't have much experiance in DB programming. I
hope I can get some guidence from this group. Most probably there are
better solutions from what I'm trying to do. Any help would be very much

Regards & TIA,