Question

我有一个抓取工具，可以扫描网页中的所有字词。然后它将每个单词与它所属的url一起插入到mysql数据库中。然后根据文档中找到的单词数量对搜索进行排序。问题是......如何在现有查询中添加多个术语查询。

它非常适合单项查询，但我希望我的查询在同一网页中尝试查找单词，如果网页中没有任何单词，则返回正常条款的结果。

我的查询如下：

         $results = addslashes( $_POST['results'] );

               " SELECT p.page_url AS url,
                       COUNT(*) AS occurrences 
                       FROM page p, word w, occurrence o
                       WHERE p.page_id = o.page_id AND
                       w.word_id = o.word_id AND
                       w.word_word = \"$keyword\"
                       GROUP BY p.page_id
                       ORDER BY occurrences DESC
                       LIMIT $results"

Answer 1

使用COUNT(DISTINCT ...)计算每页上找到的不同字词的数量，并使用IN查找任何字词列表：

SELECT
    p.page_url AS url,
    COUNT(DISTINCT w.word_word) AS words_found
    COUNT(*) AS occurrences 
FROM page p
JOIN occurrence o ON p.page_id = o.page_id
JOIN word w ON w.word_id = o.word_id
WHERE w.word_word IN ('foo', 'bar')
GROUP BY p.page_id
ORDER BY occurrences DESC

如果您想确保页面上至少有n个搜索字词，请添加HAVING子句：

GROUP BY p.page_id
HAVING COUNT(DISTINCT w.word_word) >= 2
ORDER BY occurrences DESC

Answer 2

如果数据库引擎支持，您可以进行子选择。例如：

SELECT 
  url, 
  (select count(*) from table where conditions1) as count1, 
  (select count(*) from table where conditions2) as count2 
 FROM table

多项搜索查询

2 个答案: