Mysql使用全文索引(FullText index)的实例代码

倒排索引（英语：Inverted index），也常被称为反向索引、置入档案或反向档案，是一种索引方法，被用来存储在全文搜索下某个单词在一个文档或者一组文档中的存储位置的映射。它是文档检索系统中最常用的数据结构。

CREATE TABLE articles (
    id INT UNSIGNED AUTO_INCREMENT NOT NULL PRIMARY KEY,
    title VARCHAR (200),
    body TEXT,
    FULLTEXT (title, body) WITH PARSER ngram
) ENGINE = INNODB DEFAULT CHARSET=utf8mb4 COMMENT='文章表';

mysql> SELECT * FROM articles WHERE MATCH (title,body) AGAINST ('精神' IN NATURAL LANGUAGE MODE);
+----+-----------------+-------------------------+
| id | title           | body                    |
+----+-----------------+-------------------------+
|  1 | 弘扬正能量      | 贯彻党的18大精神        |
+----+-----------------+-------------------------+
1 row in set (0.00 sec)

mysql> SELECT * FROM articles WHERE MATCH (title,body) AGAINST ('精神');
+----+-----------------+-------------------------+
| id | title           | body                    |
+----+-----------------+-------------------------+
|  1 | 弘扬正能量      | 贯彻党的18大精神        |
+----+-----------------+-------------------------+
1 row in set (0.00 sec)
可以看到,搜索结果命中了一条,且在不指定搜索模式的情况下,默认模式为自然语言搜索.

show variables like '%ft_boolean_syntax%'

+-------------------+----------------+
| Variable_name     | Value          |
+-------------------+----------------+
| ft_boolean_syntax | + -><()~*:""&| |
+-------------------+----------------+
mysql> SELECT * FROM articles WHERE MATCH (title,body) AGAINST ('+精神' IN BOOLEAN MODE);
+----+-----------------+-------------------------+
| id | title           | body                    |
+----+-----------------+-------------------------+
|  1 | 弘扬正能量      | 贯彻党的18大精神        |
+----+-----------------+-------------------------+
1 row in set (0.00 sec)

mysql> SELECT * FROM articles WHERE MATCH (title,body) AGAINST ('+精神 -贯彻' IN BOOLEAN MODE);
Empty set (0.01 sec)
当搜索必须命中精神时,命中了一条数据,当在加上不能包含贯彻的时候,无命中结果.