全文索引常用查询方式
一、一般的查询格式：
select * from article_detail where
contains(content_text,'发觉')>0
and rownum<11;
select * from article_detail where
contains(content_text,'هؤلاء المظلومين')>0
and rownum<11;
二、包括查询操作符的
select * from mark_tab where
contains(text,'قوامها وفعاليتها وع%ائها')>0
and rownum<11;
2. near
语法：NEAR((word1, word2,..., wordn) [, max_span [, order]])
max_span最大是100，默认也是100.
例子：
Text下有：The dog chases the cat.好人一生平安
select * from mark_tab where
contains(text,'near((好人,平安),6,true)')>0
and rownum<11;
表示“好人”和“平安”之间最大长度不能超过6,并且排序。
select * from mark_tab where
contains(text,'near((اختلفت,中国),100,false)')>0
and rownum<11;
查询有 '南京路' 字样的地址
SELECT student_id,student_name
FROM students
WHERE CONTAINS( address, 'nanjing NEAR road' )
remark: 上面的查询将返回包含 'nanjing road'，'nanjing east road'，'nanjing west road' 等字样的地址。
A NEAR B，就表示条件： A 靠近 B。
3. and, or, not
select * from mark_tab where
contains(text,'dog and cat and 好人')>0 and rownum<11;
select * from mark_tab where
contains(text,'والاحساس and العمل and 中国')>0
and rownum<11;
select * from mark_tab where
contains(text,'dog | cat | 好人')>0
and rownum<11;
4. Fuzzy
Use the fuzzy operator to expand queries to include words that are spelled similarly to the specified term。
语法：fuzzy(term, score, numresults, weight)
| Parameter |
Description |
| term |
Specify the word on which to perform the fuzzy expansion. Oracle Text expands term to include words only in the index. The word needs to be at least 3 characters for the fuzzy operator to process it. |
| score |
Specify a similarity score. Terms in the expansion that score below this number are discarded. Use a number between 1 and 80. The default is 60. |
| numresults |
Specify the maximum number of terms to use in the expansion of term. Use a number between 1 and 5000. The default is 100. |
| weight |
Specify WEIGHT or W for the results to be weighted according to their similarity scores. Specify NOWEIGHT or N for no weighting of results. |
Supported Languages
Oracle Text supports fuzzy definitions for English, French, German, Italian, Dutch, Spanish, Portuguese, Japanese, OCR, and auto-language detection.
select * from mark_tab where
contains(text,'fuzzy(google, 70, 6, weight)')>0
and rownum<11;
查询结果：The dog chases the cat.好人一生平安 goole.com baidu
阿语试了几个不成功，也不知道哪些才是相似的，不知该怎样测试。
网上资料说fuzzy不支持阿拉伯语：
Is there no way to make a "fuzzy matching" with my context index on Arabic words?, I mean what can I do to get the alternatives/matched words in a specific column (Arabic values) for a search text?
The only thing I can think of is to create your own thesaurus using ctx_thes.create_relation and add the matching words in pairs using ctx_thes.create_relation, making them synonyms, so that you can use ctx_thes.syn on your search string to obtain all of the possibilities.
5. SYNonym (SYN)
| Syntax |
Description |
| SYN(term[,thes]) |
Expands a query to include all the terms defined in the thesaurus as synonyms for term. |
From:
http://download.oracle.com/docs/cd/B28359_01/text.111/b28304/cthes.htm#i997464
步骤：
--创建名为'DEFAULT'的同义词词典，同义词不区分大小写
begin
CTX_THES.CREATE_THESAURUS('DEFAULT',False);
end;
--添加同义词（关系）
begin
ctx_thes.create_relation('DEFAULT','google','SYN','googel');
end;
begin
ctx_thes.create_relation('DEFAULT','المجتمعات','SYN','سطحية');
end;
--查看同义词（关系）
declare
synonyms varchar2(2000);
begin
synonyms := CTX_THES.SYN('google','DEFAULT');
dbms_output.put_line('the synonym expansion for google is: '||synonyms);
end;
--删除同义词（关系），整个不可用
begin
CTX_THES.DROP_RELATION('DEFAULT','google','SYN','googe');
end;
--删除某个词
begin
ctx_thes.drop_phrase('DEFAULT', 'GOOGEL');
end;
----查询测试，英文，阿文，中文都测试成功
select * from mark_tab where
contains(text,'SYN(dog)')>0
and rownum<11;
select * from mark_tab where
contains(text,'SYN(سطحية)')>0
and rownum<11;
select * from mark_tab where
contains(text,'SYN(中国)')>0
and rownum<11;
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