Forum PHP.pl

Cześć. Gdy wykonuję zapytanie:

[SQL] pobierz, plaintext 
SELECT  `users`.`uid` AS  `uid` ,  `login` ,  `reg_timestamp` ,  `rank` ,  `server_respect` ,  `forum_respect` ,  `last_visit_timestamp` ,  `accsongs` ,  `rejsongs` , `waitsongs` 
FROM  `users` 
LEFT JOIN (
 
SELECT IFNULL (COUNT( * ), 0) AS  `waitsongs` ,  `uid` 
FROM  `songs` 
WHERE  `status` =0
GROUP BY  `uid`
) AS  `waitsongs` ON  `waitsongs`.`uid` =  `users`.`uid` 
LEFT JOIN (
 
SELECT  IFNULL (COUNT( * ), 0) AS  `accsongs` ,  `uid` 
FROM  `songs` 
WHERE  `status` =1
GROUP BY  `uid`
) AS  `accsongs` ON  `accsongs`.`uid` =  `users`.`uid` 
LEFT JOIN (
 
SELECT  IFNULL (COUNT( * ), 0) AS  `rejsongs` ,  `uid` 
FROM  `songs` 
WHERE  `status` =2
GROUP BY  `uid`
) AS  `rejsongs` ON  `rejsongs`.`uid` =  `users`.`uid` 
WHERE (
`waitsongs` +  `accsongs` +  `rejsongs`
) > 0
ORDER BY  `reg_timestamp` DESC 
LIMIT 0 , 30
[SQL] pobierz, plaintext 

to nie zwraca nic, natomiast jak wykonuję:

[SQL] pobierz, plaintext 
SELECT  `users`.`uid` AS  `uid` ,  `login` ,  `reg_timestamp` ,  `rank` ,  `server_respect` ,  `forum_respect` ,  `last_visit_timestamp` ,  `accsongs` ,  `rejsongs` , `waitsongs` 
FROM  `users` 
LEFT JOIN (
 
SELECT IFNULL (COUNT( * ), 0) AS  `waitsongs` ,  `uid` 
FROM  `songs` 
WHERE  `status` =0
GROUP BY  `uid`
) AS  `waitsongs` ON  `waitsongs`.`uid` =  `users`.`uid` 
LEFT JOIN (
 
SELECT  IFNULL (COUNT( * ), 0) AS  `accsongs` ,  `uid` 
FROM  `songs` 
WHERE  `status` =1
GROUP BY  `uid`
) AS  `accsongs` ON  `accsongs`.`uid` =  `users`.`uid` 
LEFT JOIN (
 
SELECT  IFNULL (COUNT( * ), 0) AS  `rejsongs` ,  `uid` 
FROM  `songs` 
WHERE  `status` =2
GROUP BY  `uid`
) AS  `rejsongs` ON  `rejsongs`.`uid` =  `users`.`uid` 
WHERE 
`waitsongs` > 0
ORDER BY  `reg_timestamp` DESC 
LIMIT 0 , 30
[SQL] pobierz, plaintext 

to zwraca to co trzeba. Dlaczego tak się dzieje? W klauzuli WHERE nie można stosować rzeczy typu coś + coś + coś > czegoś?