更改MySQL数据库的字符集会导致SELECT问题？

I would like to look up data from my table, which includes varchar strings with mutations like "ö, ü, ä", so I've changed the charset to "utf8_general_ci" (because I expected, it'll work), but when I send a query to the table like

SELECT * FROM table WHERE column='%ü%'

it returns all rows in the table, even if the cell doesn't contain any 'ü'.

Why does it return every row and how can I fix it?

There may be a better solution but this might help

SELECT * FROM table WHERE column='%ü%' collate utf8_bin