Question

我的MySQL语句有问题。

我有这个：

SELECT ad.*, 
  (SELECT img.image 
   FROM '.$this->config->db_prefix.'_images AS img 
   WHERE img.aid = ad.aid LIMIT 1) AS img 
FROM '.$this->config->db_prefix.'_adverts ad 
WHERE fid = :fid 
ORDER BY cr_date DESC

哪个工作正常，但我需要从_images表中获取所有图片，所以如果我删除LIMIT 1我就会

Cardinality violation: 1242 Subquery returns more than 1 row

SQL的结果输出为JSON。

Answer 1

你遇到的问题是，当你说一个select时，mysql希望一次得到一个条目。看看mysql JOIN语句。

http://dev.mysql.com/doc/refman/5.0/en/join.html

select ad.*, img.image 
from TABLE1 ad 
JOIN TABLE2 img on ad.aid = img.aid 
WHERE CONDITION 
ORDER BY cr_date DESC.

Answer 2

您可以使用GROUP_CONCAT() MySQL聚合函数：

SELECT ad.*, (SELECT GROUP_CONCAT(img.image) FROM '.$this->config->db_prefix.'_images AS img WHERE img.aid = ad.aid) AS img FROM '.$this->config->db_prefix.'_adverts ad WHERE fid = :fid ORDER BY cr_date DESC

然后explode()在php或split()以后在javascript中。

在mysql子查询中LIMIT

2 个答案: