How to combine data from 2 different excel and reference it to a specific list of data

[Novelchew]

There is two excel files that i want to load them together. [File A and B]

These files contains 2 column. New ID number and Old ID number.

I need to combine these 2 excel together, once they are combined together i have a another file with only 100 OLD ID Number.

I need to find the new ID number for these 100 ID from file A and B.
Table C is the main data i want to keep.

TableA:
LOAD [OLD ID XXX] as [OLD ID],
[NEW ID]

FROM
xxxx
(txt, utf8, embedded labels, delimiter is ',', msq);

Join (TableA)

TableB:
LOAD [OLD ID XXX] as [OLD ID],
[NEW ID]

FROM
xxxx
(txt, utf8, embedded labels, delimiter is ',', msq);

left join

TableC:
LOAD [ID NUMBER] as [OLD ID],
FROM
XXXX

[villegasi03]

I might be missing something but if you concatenate both files and then join in the 100 id file by the old ID field you should be able to see where they match.