You can run this command from the DB2 command line processor (CLP) or from inside a SQL application by calling the ADMIN_CMD stored procedure
EXPORT TO result.csv OF DEL MODIFIED BY NOCHARDEL
SELECT col1, col2, coln FROM testtable;
There are lots of options for IMPORT and EXPORT that you can use to create a data file that meets your needs. The NOCHARDEL qualifier will suppress double quote characters that would otherwise appear around each character column.
Keep in mind that any SELECT statement can be used as the source for your export, including joins or even recursive SQL. The export utility will also honor the sort order if you specify an ORDER BY in your SELECT statement.