MySQL 8.0

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CREATE TABLE test (txt VARCHAR(2))
SELECT 'Aa' txt UNION ALL SELECT 'aA' UNION ALL SELECT 'Bb';
SELECT * FROM test;

txt

Aa

aA

Bb

SELECT txt COLLATE utf8mb4_0900_ai_ci, COUNT(*)
FROM test 
GROUP BY 1;

txt COLLATE utf8mb4_0900_ai_ci
COUNT(*)

Aa
2

Bb
1

SELECT txt COLLATE utf8mb4_0900_bin, COUNT(*)
FROM test 
GROUP BY 1;

txt COLLATE utf8mb4_0900_bin
COUNT(*)

Aa
1

aA
1

Bb
1