#1242 - 子查询返回超过1行 - mysql

Question

我正在尝试创建一个select语句,从MySQL数据库中选择图像名称.该表名为 - pictures_archive.我也试图根据他们的类别选择这些图片.代码是:

SELECT pictures_archive_filename FROM pictures_archive 
WHERE pictures_archive_id = (SELECT pictures_archive_id 
FROM pictures_archive_category WHERE pictures_category_id = 9)

它给了我一个"#1242 - Subquery返回超过1行"的错误.我可以看到原因,但无法弄明白该怎么做.

Answer 1

由于您的子查询可以返回多个值,因此IN应该适合您的where子句.

SELECT pictures_archive_filename 
FROM pictures_archive 
WHERE pictures_archive_id IN 
(
   SELECT pictures_archive_id 
   FROM pictures_archive_category 
   WHERE pictures_category_id = 9
)

另一种选择是join两个表更有效.

SELECT  pictures_archive_filename 
FROM    pictures_archive a 
        INNER JOIN pictures_archive_category b
            ON a.pictures_archive_id = b.pictures_archive_id
WHERE   b.pictures_category_id = 9