SQLite 使用 GROUP BY 而不区分大小写

Question

I have got a column for Email adresses in my table, where it's possibile for the adresses to be all lower case, all upper case, camelcase, etc. How can I modify my query so, that adresses like example@gmail.com and EXAMPLE@GMAIL.COM will be grouped together.

Thats my actual query:

SELECT count(Email) as Number, Email
FROM tbl_SAP_Users
GROUP BY Email
HAVING Number > 1
ORDER BY Number DESC;

Answer 1

You can group by lower(Email) :

SELECT count(*) as Number, lower(Email) Email
FROM tbl_SAP_Users
GROUP BY lower(Email)
HAVING Number > 1
ORDER BY Number DESC;

Or use COLLATE NOCASE in the GROUP BY clause:

SELECT count(*) as Number, Email
FROM tbl_SAP_Users
GROUP BY Email COLLATE NOCASE
HAVING Number > 1
ORDER BY Number DESC;

Answer 2

You could try the LOWER() function to make them all lower case.

You might also want to use TRIM() to address whitespace at either end.

SELECT count(Email) as Number, Email
FROM tbl_SAP_Users
GROUP BY LOWER(TRIM(Email))
HAVING Number > 1
ORDER BY Number DESC;