# Introduction to full-text operators and basic search
在本教程中，我们将探讨Manticore Search中可用的全文搜索运算符。
# 全文搜索运算符和基本搜索简介
Manticore Search中的所有搜索操作都基于标准布尔运算符（AND，OR，NOT），这些运算符可以组合使用并以任意顺序排列，以组合或排除关键词以获得更相关的结果。
默认且最简单的全文搜索运算符是AND，当您只需在搜索中列出几个词时，就会默认使用该运算符。
**AND** 是默认运算符，使用 **`fast slow`** 查询将返回同时包含两个词项 'fast' 和 'slow' 的文档。如果一个词项在文档中存在而另一个不存在，该文档将不会包含在结果列表中。
默认情况下，词语将在所有可用的全文字段中进行搜索。
```sql
SELECT * FROM testrt WHERE MATCH('fast slow');
```
**OR** 用于匹配任意一个词项（或两个都匹配）。词项需要用竖线分隔，例如 **`fast | slow`**。它将找到包含 `fast` 或 `slow` 的文档。
```sql
SELECT * FROM testrt WHERE MATCH('fast | slow');
```
OR 运算符的优先级高于 AND，因此查询 **'find me fast|slow'** 可以被解释为 'find me (fast|slow)'：
```sql
SELECT * FROM testrt WHERE MATCH('find me fast | slow');
```
 **NOT** 确保用 `-` 或 `!` 标记的词项不在结果中。任何包含此类词项的文档都将被排除。例如 **`fast !slow`** 将找到包含 `fast` 的文档，但前提是其中没有 `slow`。在尝试减少搜索范围时要小心使用它，因为它可能会变得过于具体并排除掉好的文档。
```sql
SELECT * FROM testrt WHERE MATCH('find !slow');
SELECT * FROM testrt WHERE MATCH('find -slow');
```
**MAYBE** 是一个特殊运算符，其工作方式类似于 `OR`，但要求左侧的词项始终出现在结果中，而右侧的词项是可选的。但是当两个词项都满足时，文档将获得更高的搜索排名。例如 **`fast MAYBE slow`** 将找到包含 `fast` 或 `slow` 的文档，但同时包含两个词项的文档将获得更高的评分。
```sql
SELECT * FROM testrt WHERE MATCH('find MAYBE slow');
```
## 使用示例
让我们使用mysql客户端连接到Manticore：
```sql
# mysql -P9306 -h0
```
对于布尔搜索，可以使用 OR 运算符 `|`：
```sql
MySQL [(none)]> select * from testrt where match('find | me fast');
+------+------+------------------------+----------------+
| id | gid | title | content |
+------+------+------------------------+----------------+
| 1 | 1 | find me | fast and quick|
| 2 | 1 | find me fast | quick |
| 6 | 1 | find me fast now | quick |
| 5 | 1 | find me quick and fast | quick |
+------+------+------------------------+----------------+
4 rows in set (0.00 sec)
```
OR 运算符的优先级高于 AND，查询 `find me fast|slow` 被解释为 `find me (fast|slow)`：
```sql
MySQL [(none)]> SELECT * FROM testrt WHERE MATCH('find me fast|slow');
+------+------+------------------------+----------------+
| id | gid | title | content |
+------+------+------------------------+----------------+
| 1 | 1 | find me | fast and quick|
| 2 | 1 | find me fast | quick |
| 6 | 1 | find me fast now | quick |
| 3 | 1 | find me slow | quick |
| 5 | 1 | find me quick and fast | quick |
+------+------+------------------------+----------------+
5 rows in set (0.00 sec)
```
对于否定，运算符 NOT 可以指定为 `-` 或 `!`：
```sql
MySQL [(none)]> select * from testrt where match('find me -fast');
+------+------+--------------+---------+
| id | gid | title | content |
+------+------+--------------+---------+
| 3 | 1 | find me slow | quick |
+------+------+--------------+---------+
1 row in set (0.00 sec)
```
必须注意，默认情况下Manticore不支持完整的否定查询，因此无法仅运行 `-fast`（从v3.5.2版本开始将支持）。
另一个基本运算符是 `MAYBE`。由 MAYBE 定义的词项可以在文档中存在或不存在。如果存在，它将影响排名，包含它的文档将获得更高的排名。
```sql
MySQL [(none)]> select * from testrt where match('find me MAYBE slow');
+------+------+------------------------+----------------+
| id | gid | title | content |
+------+------+------------------------+----------------+
| 3 | 1 | find me slow | quick |
| 1 | 1 | find me | fast and quick|
| 2 | 1 | find me fast | quick |
| 5 | 1 | find me quick and fast | quick |
| 6 | 1 | find me fast now | quick |
+------+------+------------------------+----------------+
5 rows in set (0.00 sec)
```
## 字段运算符
如果我们想将搜索限制在特定字段，可以使用运算符 '@'：
```sql
mysql> select * from testrt where match('@title find me fast');
+------+------+------------------------+---------+
| id | gid | title | content |
+------+------+------------------------+---------+
| 2 | 1 | find me fast | quick |
| 6 | 1 | find me fast now | quick |
| 5 | 1 | find me quick and fast | quick |
+------+------+------------------------+---------+
3 rows in set (0.00 sec)
```
我们也可以指定多个字段来限制搜索：
```sql
mysql> select * from testrt where match('@(title,content) find me fast');
+------+------+------------------------+----------------+
| id | gid | title | content |
+------+------+------------------------+----------------+
| 1 | 1 | find me | fast and quick |
| 2 | 1 | find me fast | quick |
| 6 | 1 | find me fast now | quick |
| 5 | 1 | find me quick and fast | quick |
+------+------+------------------------+----------------+
4 rows in set (0.00 sec)
```
字段运算符还可以用于限制搜索仅在前x个词中进行。例如：
```sql
mysql> select * from testrt where match('@title lazy dog');
+------+------+----------------------------------------------------------------------------+---------------------------------------+
| id | gid | title | content |
+------+------+----------------------------------------------------------------------------+---------------------------------------+
| 4 | 1 | The quick brown fox jumps over the lazy dog | The five boxing wizards jump quickly |
| 7 | 1 | The quick brown fox take a step back and jumps over the lazy dog | The five boxing wizards jump quickly |
| 8 | 1 | The brown and beautiful fox take a step back and jumps over the lazy dog | The five boxing wizards jump quickly |
+------+------+----------------------------------------------------------------------------+---------------------------------------+
4 rows in set (0.00 sec)
```
但是如果我们只在前5个词中搜索，我们将找不到任何结果：
```sql
mysql> select * from testrt where match('@title[5] lazy dog');
Empty set (0.00 sec)
```
在某些情况下，搜索可能需要在多个索引上执行，而这些索引可能没有相同的全文字段。
默认情况下，如果指定的字段在索引中不存在，将导致查询错误。为了解决这个问题，可以使用特殊运算符 `@@relaxed`：
```sql
mysql> select * from testrt where match('@(title,keywords) lazy dog');
ERROR 1064 (42000): index testrt: query error: no field 'keywords' found in schema
```
```sql
mysql> select * from testrt where match('@@relaxed @(title,keywords) lazy dog');
+------+------+----------------------------------------------------------------------------+---------------------------------------+
| id | gid | title | content |
+------+------+----------------------------------------------------------------------------+---------------------------------------+
| 4 | 1 | The quick brown fox jumps over the lazy dog | The five boxing wizards jump quickly |
| 7 | 1 | The quick brown fox take a step back and jumps over the lazy dog | The five boxing wizards jump quickly |
| 8 | 1 | The brown and beautiful fox take a step back and jumps over the lazy dog | The five boxing wizards jump quickly |
+------+------+----------------------------------------------------------------------------+---------------------------------------+
3 rows in set, 1 warning (0.01 sec)
```
## 模糊搜索
模糊匹配允许仅匹配查询字符串中的一些词，例如：
```sql
mysql> select * from testrt where match('"fox bird lazy dog"/3');
+------+------+----------------------------------------------------------------------------+---------------------------------------+
| id | gid | title | content |
+------+------+----------------------------------------------------------------------------+---------------------------------------+
| 4 | 1 | The quick brown fox jumps over the lazy dog | The five boxing wizards jump quickly |
| 7 | 1 | The quick brown fox take a step back and jumps over the lazy dog | The five boxing wizards jump quickly |
| 8 | 1 | The brown and beautiful fox take a step back and jumps over the lazy dog | The five boxing wizards jump quickly |
+------+------+----------------------------------------------------------------------------+---------------------------------------+
3 rows in set (0.00 sec)
```
在这种情况下，我们使用 `QUORUM` 运算符并指定匹配3个词即可。使用 `/1` 的搜索等同于OR布尔搜索，而使用 `/N` 的搜索（其中N是输入词的数量）等同于AND搜索。
除了绝对数字，您还可以指定0.0到1.0之间的数字（代表0%到100%），Manticore将仅匹配至少包含指定百分比的给定词的文档。上面的相同示例也可以写成 `"fox bird lazy dog"/0.3`，它将匹配至少包含4个词中30%的文档。
```sql
mysql> select * from testrt where match('"fox bird lazy dog"/0.3');
+------+------+----------------------------------------------------------------------------+---------------------------------------+
| id | gid | title | content |
+------+------+----------------------------------------------------------------------------+---------------------------------------+
| 4 | 1 | The quick brown fox jumps over the lazy dog | The five boxing wizards jump quickly |
| 7 | 1 | The quick brown fox take a step back and jumps over the lazy dog | The five boxing wizards jump quickly |
| 8 | 1 | The brown and beautiful fox take a step back and jumps over the lazy dog | The five boxing wizards jump quickly |
+------+------+----------------------------------------------------------------------------+---------------------------------------+
3 rows in set (0.00 sec)
```
## 高级运算符
除了较简单的运算符外，还有许多高级运算符使用较少，但在某些情况下可能是绝对必要的。
最常用的高级运算符之一是短语运算符。
短语运算符仅在给定的词按逐字指定的顺序找到时才匹配。这还将限制词必须出现在相同的字段中：
```sql
mysql> SELECT * FROM testrt WHERE MATCH('"quick brown fox"');
+------+------+-------------------------------------------------------------------+---------------------------------------+
| id | gid | title | content |
+------+------+-------------------------------------------------------------------+---------------------------------------+
| 4 | 1 | The quick brown fox jumps over the lazy dog | The five boxing wizards jump quickly |
| 7 | 1 | The quick brown fox take a step back and jumps over the lazy dog | The five boxing wizards jump quickly |
+------+------+-------------------------------------------------------------------+---------------------------------------+
2 rows in set (0.00 sec)
```
短语运算符的更宽松版本是严格顺序运算符。
顺序运算符要求词必须按指定的顺序找到，但允许其他词出现在它们之间：
```sql
mysql> SELECT * FROM testrt WHERE MATCH('find << me << fast');
+------+------+------------------------+---------+
| id | gid | title | content |
+------+------+------------------------+---------+
| 2 | 1 | find me fast | quick |
| 6 | 1 | find me fast now | quick |
| 5 | 1 | find me quick and fast | quick |
+------+------+------------------------+---------+
3 rows in set (0.00 sec)
```
另一对与词位置一起工作的运算符是开始/结束字段运算符。
这些将限制词必须出现在字段的开头或结尾。
```sql
mysql> SELECT * FROM testrt WHERE MATCH('^find me fast$');
+------+------+------------------------+---------+
| id | gid | title | content |
+------+------+------------------------+---------+
| 2 | 1 | find me fast | quick |
| 5 | 1 | find me quick and fast | quick |
+------+------+------------------------+---------+
2 rows in set (0.00 sec)
```
邻近运算符类似于AND运算符，但增加了词之间的最大距离，因此它们仍可被视为匹配。让我们以仅使用AND运算符的示例为例：
```sql
mysql> SELECT * FROM testrt WHERE MATCH('brown fox jumps');
+------+------+----------------------------------------------------------------------------+---------------------------------------+
| id | gid | title | content |
+------+------+----------------------------------------------------------------------------+---------------------------------------+
| 4 | 1 | The quick brown fox jumps over the lazy dog | The five boxing wizards jump quickly |
| 7 | 1 | The quick brown fox take a step back and jumps over the lazy dog | The five boxing wizards jump quickly |
| 8 | 1 | The brown and beautiful fox take a step back and jumps over the lazy dog | The five boxing wizards jump quickly |
+------+------+----------------------------------------------------------------------------+---------------------------------------+
3 rows in set (0.00 sec)
```
我们的查询返回2个结果：一个结果中所有词彼此靠近，另一个结果中有一个词更远。
如果我们希望仅在词在一定距离内时才匹配，可以使用邻近运算符来限制这一点：
```sql
mysql> SELECT * FROM testrt WHERE MATCH('"brown fox jumps"~5');
+------+------+---------------------------------------------+---------------------------------------+
| id | gid | title | content |
+------+------+---------------------------------------------+---------------------------------------+
| 4 | 1 | The quick brown fox jumps over the lazy dog | The five boxing wizards jump quickly |
+------+------+---------------------------------------------+---------------------------------------+
1 row in set (0.00 sec)
```
邻近操作符的更通用版本是 `NEAR` 操作符。在邻近情况下，会在一个词袋中指定单个距离，而 `NEAR` 操作符使用两个操作数，这两个操作数可以是单个词或表达式。
在以下示例中，'brown' 和 'fox' 必须在距离 2 内，'fox' 和 'jumps' 必须在距离 6 内：
```sql
mysql> SELECT * FROM testrt WHERE MATCH('brown NEAR/2 fox NEAR/6 jumps');
+------+------+-------------------------------------------------------------------+---------------------------------------+
| id | gid | title | content |
+------+------+-------------------------------------------------------------------+---------------------------------------+
| 4 | 1 | The quick brown fox jumps over the lazy dog | The five boxing wizards jump quickly |
| 7 | 1 | The quick brown fox take a step back and jumps over the lazy dog | The five boxing wizards jump quickly |
+------+------+-------------------------------------------------------------------+---------------------------------------+
2 rows in set (0.00 sec)
```
该查询排除了不满足第一个 `NEAR` 条件的文档（此处是最后一个）：
```sql
mysql> SELECT * FROM testrt WHERE MATCH('brown NEAR/3 fox NEAR/6 jumps');
+------+------+----------------------------------------------------------------------------+---------------------------------------+
| id | gid | title | content |
+------+------+----------------------------------------------------------------------------+---------------------------------------+
| 4 | 1 | The quick brown fox jumps over the lazy dog | The five boxing wizards jump quickly |
| 7 | 1 | The quick brown fox take a step back and jumps over the lazy dog | The five boxing wizards jump quickly |
| 8 | 1 | The brown and beautiful fox take a step back and jumps over the lazy dog | The five boxing wizards jump quickly |
+------+------+----------------------------------------------------------------------------+---------------------------------------+
3 rows in set (0.09 sec)
```
`NEAR` 操作符的一个变体是 `NOTNEAR`，它仅在操作数之间有最小距离时匹配。
```sql
mysql> SELECT * FROM testrt WHERE MATCH('"brown fox" NOTNEAR/5 jumps');
+------+------+-------------------------------------------------------------------+---------------------------------------+
| id | gid | title | content |
+------+------+-------------------------------------------------------------------+---------------------------------------+
| 7 | 1 | The quick brown fox take a step back and jumps over the lazy dog | The five boxing wizards jump quickly |
+------+------+-------------------------------------------------------------------+---------------------------------------+
1 row in set (0.00 sec)
```
Manticore 还可以检测纯文本中的句子和 HTML 内容中的段落。
为了对句子进行索引，需要启用 **[index_sp](http://mnt.cr/index_sp)** 选项，而段落还需要 **[html_strip](http://mnt.cr/html_strip)=1**。让我们以以下示例为例：
```sql
mysql> select * from testrt where match('"the brown fox" jumps')G
*************************** 1. row ***************************
id: 15
gid: 2
title: The brown fox takes a step back. Then it jumps over the lazydog
content:
1 row in set (0.00 sec)
```
该文档包含 2 个句子，而短语仅在第一个句子中找到，'jumps' 仅在第二个句子中。
使用 SENTENCE 操作符，我们可以将搜索限制为仅当操作数在同一个句子中时匹配：
```sql
mysql> select * from testrt where match('"the brown fox" SENTENCE jumps')G
Empty set (0.00 sec)
```
我们可以看到该文档不再匹配。如果我们修正搜索查询，使所有词都来自同一个句子，我们将看到匹配：
```sql
mysql> select * from testrt where match('"the brown fox" SENTENCE back')G
*************************** 1. row ***************************
id: 15
gid: 2
title: The brown fox takes a step back. Then it jumps over the lazydog
content:
1 row in set (0.00 sec)
```
为了演示 PARAGRAPH，让我们使用以下搜索：
```sql
mysql> select * from testrt where match('Samsung Galaxy');
+------+------+-------------------------------------------------------------------------------------+---------+
| id | gid | title | content |
+------+------+-------------------------------------------------------------------------------------+---------+
| 9 | 2 | Samsung Galaxy S10
Is a smartphone introduced by Samsung in 2019 | |
| 10 | 2 | Samsung
Galaxy,Note,A,J | |
+------+------+-------------------------------------------------------------------------------------+---------+
2 rows in set (0.00 sec)
```
这两个文档具有不同的 HTML 标签
如果我们添加 PARAGRAPH，只有包含搜索词在单个标签中的文档会保留。
更通用的操作符是 ZONE 及其变体 ZONESPAN。"zone" 是 HTML 或 XML 标签内的文本。
需要在 `index_zones` 设置中声明要用于区域的标签，例如 `index_zones = h*, th, title`。
例如：
```sql
mysql> select * from testrt where match('hello world');
+------+------+-------------------------------+---------+
| id | gid | title | content |
+------+------+-------------------------------+---------+
| 12 | 2 | Hello world | |
| 14 | 2 | Hello world
| |
| 13 | 2 | Hello
world
| |
+------+------+-------------------------------+---------+
3 rows in set (0.00 sec)
```
我们有 3 个文档，其中 'hello' 和 'world' 出现在纯文本中，出现在相同类型的区域中或出现在单个区域中。
```sql
mysql> select * from testrt where match('ZONE:h1 hello world');
+------+------+-------------------------------+---------+
| id | gid | title | content |
+------+------+-------------------------------+---------+
| 14 | 2 | Hello world
| |
| 13 | 2 | Hello
world
| |
+------+------+-------------------------------+---------+
2 rows in set (0.00 sec)
```
在这种情况下，这些词出现在 H1 区域中，但它们不需要在同一个区域中。如果我们想将匹配限制在单个区域，可以使用 ZONESPAN：
```sql
mysql> select * from testrt where match('ZONESPAN:h1 hello world');
+------+------+----------------------+---------+
| id | gid | title | content |
+------+------+----------------------+---------+
| 14 | 2 | Hello world
| |
+------+------+----------------------+---------+
1 row in set (0.00 sec)
```
希望从本文中，你已经了解了 Manticore 中 [全文搜索操作符](https://docs.manticoresearch.com/latest/html/searching/boolean_query_syntax.html) 的工作原理。如果你想通过实际操作来更好地学习，可以立即在浏览器中 [尝试我们的交互式课程](https://play.manticoresearch.com/fulltextintro/)。
### [交互式课程](https://play.manticoresearch.com/fulltextintro/)
[](https://play.manticoresearch.com/fulltextintro/)
如果你想了解更多关于全文匹配的内容，可以尝试我们的 "全文操作符入门" [交互式课程](https://play.manticoresearch.com/fulltextintro/)，该课程包含命令行以方便学习。