UPDATE Level SET words = REPLACE(words, "\\u00fc", "Ü");
UPDATE Level SET words = REPLACE(words, "\\u00dc", "Ü");
UPDATE Level SET words = REPLACE(words, "\\u00f6", "Ö");
UPDATE Level SET words = REPLACE(words, "\\u00df", "ß");
UPDATE Level SET words = REPLACE(words, "\\u00e4", "Ä");
UPDATE Word SET Word.used = 0;
UPDATE Word SET Word.used = 1 WHERE deleted = 0 AND (SELECT count(*) FROM Level WHERE words LIKE CONCAT("%\"", Word.word, "\"%") AND deleted = 0) > 0