MYSQL COUNT返回NULL？

我GOOGLE了我的问题，但没有得到答案。我想列出下面的SQL的所有结果，包括NULL（当COUNT（review.id）也返回0），而是我只是得到了只包含评论的地方文章的结果。MYSQL COUNT返回NULL？

$sql = "SELECT tbl_place.id, tbl_place.region_id, tbl_place.subregion_id, tbl_place.title, tbl_place.metalink, tbl_place.img_thumbnail, tbl_place.summary, tbl_place.category1_id, tbl_place.category2_id, tbl_place.category3_id, COUNT(review.id) AS total_review FROM tbl_place 
     JOIN review ON tbl_place.id = review.place_id 
     WHERE 
     tbl_place.category1_id = '32' AND 
     tbl_place.status = '1'   AND 
     review.rating != '0.00'   
     GROUP BY tbl_place.id 
     ORDER BY total_review $by 
     LIMIT $limit OFFSET $offset";

来源

2012-03-20 oit oit

可能重复[Mysql：Count记录（包括零）每月]（http://stackoverflow.com/questions/3486998/mysql-count-records-including-zero-per-month）。有很多，如果你看看：http://stackoverflow.com/search?q=[mysql]+count+zero – 2012-03-20 04:12:39

thx OMG小马，我看了一下，有一个答案！ – 2012-03-20 04:37:40

请使用左连接作为审查表而不是连接。连接默认情况下是内部连接，所以它将只接受匹配的记录。

来源

2012-03-20 04:29:55

我找到了答案！ – 2012-03-20 04:33:02

thx btw Vetrivel mp！ – 2012-03-20 04:33:24

的sql应该是：

$sql = "SELECT tbl_place.id, 
tbl_place.region_id, 
tbl_place.subregion_id, 
tbl_place.title, 
tbl_place.metalink, 
tbl_place.img_thumbnail, 
tbl_place.summary, 
tbl_place.category1_id, 
tbl_place.category2_id, 
tbl_place.category3_id, 
(SELECT COUNT(*) FROM review WHERE review.rating != '0.00' AND tbl_place.id = review.place_id) AS total_review 
FROM tbl_place WHERE 
tbl_place.category1_id = '32' AND 
tbl_place.status = '1' 
GROUP BY tbl_place.id 
ORDER BY total_review $by";

它的工作！ thx家伙！

来源

2012-03-21 03:45:34

MYSQL COUNT返回NULL？

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