为给定字符串搜索数据库的好算法

Question

我正在开发一个网络应用程序 (PHP + MySQL)，用户可以在其中通过输入一些搜索字符串来搜索其他用户。

我需要将用户的输入字符串与数据库中 'User' table 的 2 列（用户名和全名）相匹配，并且 return 最相关（20 或 50）火柴。最理想的是，我还需要考虑拼写错误。

我该如何解决这个问题？我不想在这里重新发明轮子。

Answer 1

我会用两列进行类似搜索

我的查询是这样的

select * from ( select * from user where (username like ='%{input}%' or lastName like '%{input}%')) and rownum =20

您需要编写自定义清理算法来清理输入的拼写错误

Answer 2

您可以使用 MySQL full Text search:

请看this, this, this篇文章。

我也想向你解释一下 Boolean Full Text Search; But I advise you to please go through Full Text Search using Query Expansion。

让我们看一下 table 上给出的示例 dev.mysql.com:

mysql> select * from articles;
+----+-----------------------+------------------------------------------+
| id | title                 | body                                     |
+----+-----------------------+------------------------------------------+
|  1 | PostgreSQL Tutorial   | DBMS stands for DataBase ...             |
|  2 | How To Use MySQL Well | After you went through a ...             |
|  3 | Optimizing MySQL      | In this tutorial we will show ...        |
|  4 | 1001 MySQL Tricks     | 1. Never run mysqld as root. 2. ...      |
|  5 | MySQL vs. YourSQL     | In the following database comparison ... |
|  6 | MySQL Security        | When configured properly, MySQL ...      |
+----+-----------------------+------------------------------------------+

mysql> SELECT * FROM articles WHERE MATCH (title,body)
     AGAINST ('"database comparison"' IN BOOLEAN MODE);

+----+-------------------+------------------------------------------+
| id | title             | body                                     |
+----+-------------------+------------------------------------------+
|  5 | MySQL vs. YourSQL | In the following database comparison ... |
+----+-------------------+------------------------------------------+

顺序很重要，引用的话：

mysql> SELECT * FROM articles WHERE MATCH (title,body)
     AGAINST ('"comparison database"' IN BOOLEAN MODE);

Empty set (0.01 sec)

当我们删除引号时，它将搜索包含单词 "database" 或 "comparison":

的行

mysql> SELECT * FROM articles WHERE MATCH (title,body)
     AGAINST ('database comparison' IN BOOLEAN MODE);

+----+---------------------+------------------------------------------+
| id | title               | body                                     |
+----+---------------------+------------------------------------------+
|  1 | PostgreSQL Tutorial | DBMS stands for DataBase ...             |
|  5 | MySQL vs. YourSQL   | In the following database comparison ... |
+----+---------------------+------------------------------------------+

现在顺序无关紧要：

mysql> SELECT * FROM articles WHERE MATCH (title,body)
     AGAINST ('comparison database' IN BOOLEAN MODE);

+----+---------------------+------------------------------------------+
| id | title               | body                                     |
+----+---------------------+------------------------------------------+
|  1 | PostgreSQL Tutorial | DBMS stands for DataBase ...             |
|  5 | MySQL vs. YourSQL   | In the following database comparison ... |
+----+---------------------+------------------------------------------+

如果我们想要获取包含单词 "PostgreSQL" 或短语 "database comparison" 的行，我们应该使用此请求：

mysql> SELECT * FROM articles WHERE MATCH (title,body)
     AGAINST ('PostgreSQL "database comparison"' IN BOOLEAN MODE);

+----+---------------------+------------------------------------------+
| id | title               | body                                     |
+----+---------------------+------------------------------------------+
|  1 | PostgreSQL Tutorial | DBMS stands for DataBase ...             |
|  5 | MySQL vs. YourSQL   | In the following database comparison ... |
+----+---------------------+------------------------------------------+

Fiddle To Try

确保您要搜索的词不在 list of stopwords 中，它们将被忽略。
（显然像 'is'、'the' 这样的词是 stopwords 并且这些被忽略了）

要在布尔模式下增强结果排序，您可以使用以下查询：

（假设你在用户输入的字符串中总共有 2 个单词）那么。

SELECT column_names, MATCH (text) AGAINST ('word1 word2')
AS col1 FROM table1
WHERE MATCH (text) AGAINST ('+word1 +word2' in boolean mode) 
order by col1 desc;

(如果你在用户输入的字符串中有3个词)那么..

SELECT column_names, MATCH (text) AGAINST ('word1 word2 word3')
AS col1 FROM table1
WHERE MATCH (text) AGAINST ('+word1 +word2 +word3' in boolean mode) 
order by col1 desc;

首先使用MATCH()我们得到非布尔搜索模式的分数（更有特色）。 second MATCH() 确保我们真的只得到我们想要的结果（所有 3 个词）。

为给定字符串搜索数据库的好算法

Good algorithm for searching DB for a given string

mysql

database

search

text