utf16 or utf32? I'm trying to store content in a lot of languages. Some of the languages use double-wide fonts (for example, Japanese fonts are frequently twice as wide as English fonts). I'm not sure which kind of database I should be using. Any information about the differences between these four charsets...
MySQL's utf32 and utf8mb4 (as well as standard UTF-8) can directly store any character specified by Unicode; the former is fixed size at 4 bytes per character whereas the latter is between 1 and 4 bytes per character.
utf8mb3 and the original utf8 can only store the first 65,536 codepoints, which will cover CJVK (Chinese, Japanese, Vietnam, Korean), and use 1 to 3 bytes per character.
utf16 uses 2 bytes for the first 65,536 codepoints, and 4 bytes for everything else.
As for fonts, that's strictly a visual thing.
See also MySQL documentation for Unicode support.