different between || and && in a statement

Hi,

I hope theis is the last question for the next time:

1st statement:

SELECT (sum(case when dict.word = 'museum' then 1 else 0 end) 
&& sum(case when dict.word = 'immer' then 1 else 0 end)) as qu , dict.url_id
^^             FROM dict, url             WHERE url.rec_id = dict.url_id                  AND url.url LIKE '%%'
         AND dict.word in ('museum','immer')             GROUP BY dict.url_id              HAVING sum(case when
dict.word= 'museum' then 1 else 0 end) && 
 
sum(case when dict.word = 'immer' then 1 else 0 end) > 0                  ^^

The result is:

ERROR:  Unable to identify an operator '&&' for types 'int4' and 'int4'       You will have to retype this query using
anexplicit cast
 

but if a do it with :

SELECT (sum(case when dict.word = 'museum' then 1 else 0 end)
|| sum(case when dict.word = 'immer' then 1 else 0 end)) as qu , dict.url_id
^^             FROM dict, url            WHERE url.rec_id = dict.url_id                  AND url.url LIKE '%%'
       AND dict.word in ('museum','immer')            GROUP BY dict.url_id            HAVING sum(case when dict.word =
'museum'then 1 else 0 end) || 
 
sum(case when dict.word = 'immer' then 1 else 0 end) > 0                  ^^

.... all is OK

Whats the different between the logical expression && and || and is there
a way to get && working?

Thanks for any hints. I hope the isn't a stupid question.

Christian

-- Christian Guenther                              Kunsthistoriker Fax: +49 030 4464152             E-mail:
cg@kunst-und-kultur.deTel:+49 030 4442931                http://kunst-und-kultur.de/     Museen, Kuenstler,
Ausstellungen,Kunstprojekte ....