Question

我有一个包含记录的表，它有一个名为gallery的表。我插入了太多照片，我想从每个图库中只选择2张随机照片。

这里是我的结构化

CREATE TABLE IF NOT EXISTS `gallery` (
`gallery_id` int(11) NOT NULL,
  `gallery_name` varchar(100) NOT NULL,
  `gallery_name_seo` varchar(120) NOT NULL,
  `gallery_client` varchar(100) NOT NULL,
  `gallery_date` date NOT NULL,
  `gallery_type` int(2) NOT NULL,
  `gallery_desc` text,
  `gallery_publish` char(1) NOT NULL DEFAULT 'N' COMMENT 'Y = Yes & N = No',
  `gallery_added` datetime NOT NULL DEFAULT '0000-00-00 00:00:00',
  `deleted` int(11) NOT NULL DEFAULT '0'
) ENGINE=MyISAM AUTO_INCREMENT=3 DEFAULT CHARSET=latin1;

这里是另一张表

CREATE TABLE IF NOT EXISTS `gallery_photo` (
`id` int(10) NOT NULL,
  `id_gallery` int(10) NOT NULL,
  `file_name` varchar(255) NOT NULL,
  `file_added` date NOT NULL,
  `deleted` smallint(6) NOT NULL DEFAULT '0'
) ENGINE=InnoDB AUTO_INCREMENT=24 DEFAULT CHARSET=latin1;

这里有许多例子，但我很难理解，

如何根据我的问题创建查询。？

谢谢

Answer 1

以下查询会为每个id_gallery提供1张随机照片：

SELECT * 
FROM (SELECT * FROM `gallery_photo` ORDER BY RAND()) as `rand_photos`
GROUP BY rand_photos.id_gallery

你可以自己UNION为每个画廊获取2张随机照片：

SELECT * 
FROM (SELECT * FROM `gallery_photo` ORDER BY RAND()) as `rand_photo1`
GROUP BY rand_photo1.id_gallery
UNION
SELECT * 
FROM (SELECT * FROM `gallery_photo` ORDER BY RAND()) as `rand_photo2`
GROUP BY rand_photo2.id_gallery
ORDER BY id_gallery

MYSQL QUERY：从每张专辑的表格中选择1行照片

1 个答案: