Hello Stefan, > I expect that an accent insensitive compare treats accented characters > as the "same" as their un-accented counterparts because the accent > does not change the character itself but things like pronounciation or > stress. > > So in Frech, à is similar to a, é is similar to è and you use an > accent insensitive compare to find Gérard even though your search term > says Gerard (without the accent). > > However, in the German language, the letters Ö and O are two different > characters with a completely different pronounciation (the same is > true for A/Ä and U/Ü). As they look similar, the sorting is done so > that they stay together, but they can _not_ be treated as accented > versions of each other.
UNICODE_CI_AI is a generic, language-independent collation. Since ö, ü and ä are not specific to German (they also exist in Dutch, for instance, and ö and ä in Swedish, and ö and ü in Hungarian, etc.) it will simply treat them as accented forms of o, u and a. Also, it is questionable if you should consider a and ä different letters, even in German. See e.g. https://de.wikipedia.org/wiki/Alphabetische_Sortierung DIN 5007 Variante 1 (für Wörter verwendet, etwa in Lexika; Abschnitt 6.1.1.4.1) ä und a sind gleich ö und o sind gleich ü und u sind gleich ß und ss sind gleich DIN 5007 Variante 2 (spezielle Sortierung für Namenslisten, etwa in Telefonbüchern; Abschnitt 6.1.1.4.2) ä und ae sind gleich ö und oe sind gleich ü und ue sind gleich ß und ss sind gleich If you do want to treat them as different letters, you need a German collation that does just that. However, this collation will not work correctly with words in some other languages containing ä, ö and ü. Cheers, Paul Vinkenoog
