problem to count (distinct number)

Hi,

I have a table with a column (int4), and I want to know how many
different numbers there are. In an example book I saw the query

SELECT COUNT (DISTINCT data ) FROM media;

by then I get

ERROR: parser: parse error at or near "distinct"

Is the query in error or does PostgreSQL not support this? How do I
then get the number of distinct data from my table?

TIA,

Micce

--
Mikael Hedin, MSc +46 (0)980 79176
Swedish Institute of Space Physics +46 (0)8 344979 (home)
S-Box 812, 981 28 KIRUNA, Sweden +46 (0)70 5891533 (mobile)