strange behaviour

Hi

could someone explain this to me :

sympa=> select count(*) from subscriber_table;
  count
-------
  14029
sympa=> select count(*) from subscriber_table where bounce_subscriber =
NULL;
  count
-------
  14024
sympa=> select count(*) from subscriber_table where bounce_subscriber <> NULL;
  count
-------
      0
sympa=> select count(*) from subscriber_table where bounce_subscriber = '';
  count
-------
      0
sympa=> select count(*) from subscriber_table where bounce_subscriber <> '';
  count
-------
      5

I was thinking that "= NULL" and "<> NULL" were oposite and that "<> NULL"
would give me the result i had with "<> ''" or am I mistaken ?

--
Mathieu Arnold