Find duplicates in case-sensitive query in MS Access

Question

I have a table containing Japanese text, in which I believe that there are some duplicate rows. I want to write a SELECT query that returns all duplicate rows. So I tried running the following query based on an answer from this site (I wasn't able to relocate the source):

SELECT [KeywordID], [Keyword]
FROM Keyword
WHERE [Keyword] IN (SELECT [Keyword]
FROM [Keyword] GROUP BY [Keyword] HAVING COUNT(*) > 1);

The problem is that Access' equality operator treats the two Japanese writing systems - hiragana and katakana - as the same thing, where they should be treated as distinct. Both writing systems have the same phonetic value, although the written characters used to represent the sound are different - eg あ (hiragana) and ア (katakana) both represent the sound 'a'.

When I run the above query, however, both of these characters will appear, as according to Access, they're the same character and therefore a duplicate. Essentially it's a case-insensitive search where I need a case-sensitive one.

I got around this issue when doing a simple SELECT to find a Keyword using StrComp to perform a binary comparison , because this method correctly treats hiragana and katakana as distinct. I don't know how I can adapt the query above to use StrComp, though, because it's not directly evaluating one string against another as in the linked question.

Basically what I'm asking is: how can I do a query that will return all duplicates in a table, case-sensitive?

Answer 1

You can use exists instead:

SELECT [KeywordID], [Keyword]
FROM Keyword as k
WHERE EXISTS (SELECT 1
              FROM Keyword as k2
              WHERE STRCOMP(k2.Keyword, k.KeyWord, 0) = 0 AND
                    k.KeywordID <> k2.KeywordID
             );

Answer 2

Try with a self join:

SELECT k1.[KeywordID], k1.[Keyword], k2.[KeywordID], k2.[Keyword]
FROM Keyword AS k1 INNER JOIN Keyword AS k2
ON k1.[KeywordID] < k2.[KeywordID] AND STRCOMP(k1.[Keyword], k2.[Keyword], 0) = 0