我需要下载类似的结果。详细写下，如果我从“files”表的特定文件写入数据，我希望看到其他文件下面有相同的记录“id_tag_main”。我有桌子：标签id | name | 1 one 2 two 3 three 标签文件id | id_tag | id_file | id_tag_main 1 1 1 3 2 - 2 2 3 - 3 2 4 - 4 2文件id | name | 1 city 2 vehicles 3 weather 4 gifts我需要 Mysql php 查询，我尝试了 LEFT JOIN 但结果不正确。如果我从文件“车辆”中选择，那么车辆有"id_tag_main" = 2并且我想要更多文件在哪里"id_tag_main" = 2
2 回答
HUWWW
TA贡献1874条经验 获得超12个赞
如果您只能从文件中选择车辆，那么您需要执行以下查询
SELECT f.name
FROM tags_files tf INNER JOIN files f ON tf.id_file = f.id
WHERE id_tag_main = (SELECT id_tag_main
FROM tags_files
WHERE id_file = (SELECT id FROM files WHERE name = 'vehicles' ));
CREATE TABLE tags_files (
`id` int,
`id_tag` int,
`id_file` int,
`id_tag_main` int
);
INSERT INTO tags_files
(`id`, `id_tag`, `id_file`, `id_tag_main`)
VALUES
('1', '1', '1', '3'),
('2', NULL, '2', '2'),
('3 ', NULL, '3', '2'),
('4', NULL, '4', '2');
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CREATE TABLE files (
`id` int,
`name` VARCHAR(14)
);
INSERT INTO files
(`id`, `name`)
VALUES
('1', 'city'),
('2', 'vehicles'),
('3', 'weather'),
('4', 'gifts');
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CREATE TABLE tags (
`id` int,
`name` VARCHAR(11)
);
INSERT INTO tags
(`id`, `name`)
VALUES
('1', 'one'),
('2', 'two'),
('3', 'three');
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SELECT f.name
FROM tags_files tf INNER JOIN files f ON tf.id_file = f.id
WHERE id_tag_main = (SELECT id_tag_main
FROM tags_files
WHERE id_file = (SELECT id FROM files WHERE name = 'vehicles' ));
| 姓名 |
| :-------- |
| 车辆 |
| 天气|
| 礼品|
炎炎设计
TA贡献1808条经验 获得超4个赞
也许是这个？
select *
from files as f1
left join tags_files on tags_files.id_tag_main = f1.id
left join files as f2 on tags_files.id_file = f2.id
where f1.name = 'vehicles'
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