If you need to dump specific fields in a specific way you could run an sql statement using the
SELECT ... INTO OUTFILE 'file_name'
syntax..
eg..
SELECT field1,field2 INTO OUTFILE '/stuff/fields.txt'
FIELDS TERMINATED BY '|'
LINES TERMINATED BY '\n'
FROM mytable
WHERE field3 = 'value';
would make a textfile with the fields delimited by the '|'..
eg..
1|x
2|g
7|w
If you need to dump whole tables or databases.. have a look at the syntax for the mysqldump program that comes with mysql..
Hope this helps.
Cheers,
Tim