Question

我找不到像这样的东西

我有Sql表

tag (tag_id, tag_name..)
tags (id, tag_id, post_id)

示例：

table: tag
1 New York
2 Madrid
3 Paris
4 London

如果我的标签表填充的方式是某些帖子包含0,1,2,3或许多标签，那么如何使用搜索顺序生成sql以获得按帖子包含的标签数量排序的结果？喜欢“最佳匹配”搜索..

例如，如果我搜索3个标签“纽约”，“马德里”，“巴黎”

被驱逐的结果应该是＆gt;

Post_id's:  1,4,6,   2,3,5,   9
Where show first
    1,4,6 (has all 3 searched tags)
    then
    2,3,5 (has 2 searched tags)
    then 
    9 (with 1 searched tag)

Answer 1

试试这个：

SELECT tags.post_id, COUNT(*) AS match_count
FROM tag
JOIN tags ON tag.tag_id = tags.tag_id
WHERE tag.tag IN ('New York', 'Madrid', 'Paris')
GROUP BY tags.post_id
ORDER BY COUNT(*) DESC, tags.post_id ASC;

给出了这些结果：

+---------+-------------+
| post_id | match_count |
+---------+-------------+
|       1 |           3 |
|       4 |           3 |
|       6 |           3 |
|       2 |           2 |
|       3 |           2 |
|       5 |           2 |
|       9 |           1 |
+---------+-------------+

有了这些数据：

CREATE TABLE tag (
    tag_id INTEGER PRIMARY KEY AUTO_INCREMENT,
    tag VARCHAR(40)
);

INSERT INTO tag VALUES
(null, 'New York'),
(null, 'Madrid'),
(null, 'Paris'),
(null, 'London');

CREATE TABLE tags (
    id INTEGER PRIMARY KEY AUTO_INCREMENT,
    tag_id INTEGER,
    post_id INTEGER
);

INSERT INTO tags VALUES
(null, 1, 1),
(null, 2, 1),
(null, 3, 1),
(null, 1, 4),
(null, 2, 4),
(null, 3, 4),
(null, 1, 6),
(null, 2, 6),
(null, 3, 6),
(null, 1, 2),
(null, 2, 2),
(null, 1, 3),
(null, 2, 3),
(null, 1, 5),
(null, 2, 5),
(null, 1, 9);

按标签搜索相关性

1 个答案: