使用聚合函数进行行计数

I have a problem with counting all rows. My query is:

SELECT info.pid, Name, Addr, Phone, GROUP_CONCAT(URL) as URL
FROM info, images WHERE info.pid = images.pid AND place='$kraj' GROUP BY info.pid

I cant use mysql_num_rows since group_concat() creates a row (null values) even though there are no results.

I tried putting COUNT() inside query:

...GROUP_CONCAT(URL) as URL, COUNT(info.pid) as num FROM info...

but it counts separate rows for every join.

Any suggestions?

Why not just filter out the null values? :

SELECT info.pid, Name, Addr, Phone, GROUP_CONCAT(URL) as URL
  FROM info
  JOIN images
    ON info.pid = images.pid
 WHERE place = ...
   AND URL IS NOT NULL
 GROUP
    BY info.pid
;