php - Mysql UNIQUE KEY constraint - a and å are treated as the same characters

Question

I have a unique key on a column. When I insert a and then å it throws an error:

PHP Fatal error: Uncaught exception 'PDOException' with message 'SQLSTATE[23000]: Integrity constraint violation: 1062 Duplicate entry 'å' for key 'constraint-1'' in ..

....But a and å are different UTF characters - so what's going on....?

table has DEFAULT CHARSET=utf8mb4 and utf8mb4_unicode_ci collation.

Answer 1

latin1_swedish_ci在唯一列上使用排序规则。