Split returned recordset into unique strings

[martync]

I have a returned recordset of the format:
FieldName TableName
A Z
B Z
C Z
D Y
E Y
F Y etc
What I want to do is create a list of fieldNames for a unique tableName ie "A,B,C" for "Z" "D,E,F" for "Y"
I intend to use this information to generate a query
SELECT strFieldList FROM tbl which loops through all the combinations derived above.
Any suggestions on the most efficient way to do this from the gurus?
With thanks, Martyn