You could write a PLSQL procedure that would use the UTL_FILE package. This would give you more flexibility on how to manuver the data. You could open multiple cursors and then format then to your requirement and flush them on to a flat file.

import/export would only work if you are planning to move the data from oracle to oracle.

The select x ||','||'y'||','
FROM xyz;
would work if you are trying to flush the data from one/multiple tables, but it is possible to get the multiple entries on the same records, if there are some kind of join statments.

On the other hand if you use the UTL_FILE package, and write a procedure, then you could have single record containing all the related informations in one line.

Good luck,
Sam