You should use a Unicode collation. You can set it by default on your system, or on each field of your tables. There are the following Unicode collation names, and this are their differences:
utf8_general_ci is a very simple collation. It just
- removes all accents
- then converts to upper case
and uses the code of this sort of "base letter" result letter to compare.
utf8_unicode_ci uses the default Unicode collation element table.
The main differences are:
- utf8_unicode_ci supports so called expansions and ligatures, for example: German letter ? (U+00DF LETTER SHARP S) is sorted near "ss" Letter ? (U+0152 LATIN CAPITAL LIGATURE OE) is sorted near "OE".
utf8_general_ci does not support expansions/ligatures, it sorts all these letters as single characters, and sometimes in the wrong order.
- utf8_unicode_ci is generally more accurate for all scripts. For example, on Cyrillic block: utf8_unicode_ci is fine for all these languages: Russian, Bulgarian, Belarusian, Macedonian, Serbian, and Ukrainian. While utf8_general_ci is fine only for Russian and Bulgarian subset of Cyrillic. Extra letters used in Belarusian, Macedonian, Serbian, and Ukrainian are not sorted well.
+/- The disadvantage of utf8_unicode_ci is that it is a little bit slower than utf8_general_ci.
So depending on, if you know or not, which specific languages/characters you are going to use I do recommend that you use utf8_unicode_ci which has a more ample coverage.
Extracted from MySQL forums.
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