How to use relationships to extract data via select
Try this

select used_for_lookup.id,
        used_for_lookup.datetime,
        fid_table.fid_important_string,
        did_table.did_important_string
 from used_for_lookup 
 join fid_table on fid_table.id = used_for_lookup.fid
 join did_table on did_table.id = used_for_lookup.did
where datetime between '2014-10-09' and '2014-10-11';