如何在不区分大小写的索引中搜索区分大小写

Question

I have to query with over 100 words (case insensitive) that are stored in a separate table.

Select a_id, text from xy
inner join keywords kw on contains(xy.text, kw.word)>0

This works fine. But now I have one keyword that has to be queried case sensitive.

Does somebody know how to do that without creating a case sensitive index and query that keyword separately? Is it maybe possible to ignore a keyword, let's say 'us', and only create the index with the keyword in capital letters ('US').

I tried it with adding 'us' to the stopwords but it didn't worked out.

Answer 1

Add a column case_sensitive char(1) -- Y/N to the keywords table, then:

select a_id, text
from xy
join keywords kw on contains(xy.text, kw.word) > 0
  and (kw.case_sensitive = 'N' or instr(xy.text, kw.word) > 0)

The index will still be used, but there is an additional requirement for case sensitive keywords that the keyword must appear verbatim in the text.