Oracle中Like与Contains()之间的搜索条件差异 [英] search criteria difference between Like vs Contains() in oracle
问题描述
我创建了一个包含两列的表格.我插入了两行.
I created a table with two columns.I inserted two rows.
id name
1 narsi reddy
2 narei sia
一个是简单的数字类型，另一个是CLOB类型.因此，我决定在其上使用索引.我通过使用contains对此进行了查询. 查询:
one is simply number type and another one is CLOB type.So i decided to use indexing on that. I queried on that by using contains. query:
select * from emp where contains(name,'%a%e%')>0
2 narei sia
我希望2个人会来，但不会.但是，如果我给与喜欢，就给了我想要的东西. 查询:
I expected 2 would come,but not. But if i give same with like it's given what i wanted. query:
select * from emp where name like '%a%e%'
ID NAME
1 (CLOB) narsi reddy
2 (CLOB) narei sia
2 rows selected
最后，我了解到，就像在搜索整个文档或段落一样，但是包含的是用文字查找.
finally i understood that like is searching whole document or paragraph but contains is looking in words.
那么我如何获得所需的输出?
so how can i get required output?
推荐答案
LIKE和CONTAINS是根本不同的搜索方法.
LIKE and CONTAINS are fundamentally different methods for searching.
喜欢非常简单的字符串模式匹配器-它识别两个通配符(％)和(_)，它们分别匹配零个或多个或正好一个字符.在您的情况下，％a％e％匹配表中的两条记录-它查找零个或多个字符，后跟a，然后零个或多个字符，后跟e，然后零个或多个字符.它的返回值也非常简单:返回匹配"或不匹配"-不显示灰色阴影.
LIKE is a very simple string pattern matcher - it recognises two wildcards (%) and (_) which match zero-or-more, or exactly-one, character respectively. In your case, %a%e% matches two records in your table - it looks for zero or more characters followed by a, followed by zero or more characters followed by e, followed by zero or more characters. It is also very simplistic in its return value: it either returns "matched" or "not matched" - no shades of grey.
内容功能强大使用上下文索引的搜索工具，该工具构建了一种词树，可以使用CONTAINS搜索语法进行搜索.它可以用于搜索单个单词，单词的组合，并且具有自己的丰富语法，例如布尔运算符(AND，NEAR，ACCUM).它也更强大，它返回一个分数"，而不是返回简单的匹配"或不匹配"，可用于按相关性对结果进行排名；例如对于包含两个单词并排很近的文档，CONTAINS(col，'dog NEAR cat')将返回较高的分数.
CONTAINS is a powerful search tool that uses a context index, which builds a kind of word tree which can be searched using the CONTAINS search syntax. It can be used to search for a single word, a combination of words, and has a rich syntax of its own, such as boolean operators (AND, NEAR, ACCUM). It is also more powerful in that instead of returning a simple "matched" or "not matched", it returns a "score", which can be used to rank results in order of relevance; e.g. CONTAINS(col, 'dog NEAR cat') will return a higher score for a document where those two words are both found close together.
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