我需要下載類似的結果。詳細寫下，如果我從“files”表的特定文件寫入數據，我希望看到其他文件下面有相同的記錄“id_tag_main”。我有桌子：標簽id | name | 1 one 2 two 3 three 標簽文件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 查詢，我嘗試了 LEFT JOIN 但結果不正確。如果我從文件“車輛”中選擇，那么車輛有"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貢獻1874條經驗 獲得超12個贊
如果您只能從文件中選擇車輛，那么您需要執行以下查詢
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');
?
?
CREATE TABLE files (
`id` int,
`name` VARCHAR(14)
);
INSERT INTO files
(`id`, `name`)
VALUES
('1', 'city'),
('2', 'vehicles'),
('3', 'weather'),
('4', 'gifts');
?
?
CREATE TABLE tags (
`id` int,
`name` VARCHAR(11)
);
INSERT INTO tags
(`id`, `name`)
VALUES
('1', 'one'),
('2', 'two'),
('3', 'three');
?
?
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 |
| :-------- |
| 車輛 |
| 天氣|
| 禮品|
炎炎設計
TA貢獻1808條經驗 獲得超4個贊
也許是這個？
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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