MySQL

INTO OUTFILE

Tab separated, newline terminated...

SELECT mycol1,mycol2,mycol3

  FROM mytable

  INTO OUTFILE '/tmp/myfile.txt';

Comma separated, newline terminated, each field enclosed in double quotes...

SELECT mycol1,mycol2,mycol3

  FROM mytable

  INTO OUTFILE '/tmp/myfile.csv'

FIELDS TERMINATED BY ','

ENCLOSED BY '"'

LINES TERMINATED BY '\n'

Oracle

SPOOL

SET MARKUP csv ON DELIMITER ,

SPOOL myfile.csv

SELECT mycol1,mycol2,mycol3

  FROM mytable;

SPOOL OFF

SET COLSEP ,

SET PAGESIZE 0

SET TRIMSPOOL ON

SET HEADSEP OFF

SET LINESIZE 80

SET NUMW 10

SPOOL myfile.csv

SELECT mycol1,mycol2,mycol3

  FROM mytable;

SPOOL OFF

UTL_FILE

PostgreSQL

In psql...

SELECT mycol1,mycol2,mycol3

FROM mytable \g /tmp/myfile.txt

To append to an existing file...

SELECT mycol1,mycol2,mycol3

FROM mytable \g | cat >>/tmp/myfile.txt

Alternate method in psql...

\o /tmp/myfile.txt

SELECT mycol1,mycol2,mycol3

FROM mytable;

\o

From shell...

echo 'SELECT mycol1,mycol2,mycol3 FROM mytable' | psql myDB >> /tmp/myfile.txt

UTL_FILE