Exporting a column from a table for later import

Oracle's export utility will export all columns of a table. You cannot use exp or 10g's new Data Pump, expdp, to export only specific columns of a table. If you want to export just one column of data from a table, then I would recommend simply using SQL*Plus and spooling the output to a file, similar to the following:

spool emp_ename.txt
SELECT ename FROM scott.emp;
spool off

With the above commands in SQL*Plus, you will have a text file containing the output of just the ENAME column of the SCOTT.EMP table.