mysql - UTF-8:一般？垃圾桶？统一码？

Question

我试图弄清楚我应该对各种类型的数据使用什么排序规则。我将存储的内容 100% 是用户提交的。

我的理解是我应该使用 UTF-8 通用 CI(不区分大小写)而不是 UTF-8 二进制。但是，我找不到 UTF-8 General CI 和 UTF-8 Unicode CI 之间的明显区别。

1. 我应该将用户提交的内容存储在 UTF-8 General 还是 UTF-8 Unicode CI 列中？
2. UTF-8 二进制适用于什么类型的数据？

Answer 1

一般来说，utf8_general_ci 比 utf8_unicode_ci 快，但不太正确。

这里有区别:

For any Unicode character set, operations performed using the _general_ci collation are faster than those for the _unicode_ci collation. For example, comparisons for the utf8_general_ci collation are faster, but slightly less correct, than comparisons for utf8_unicode_ci. The reason for this is that utf8_unicode_ci supports mappings such as expansions; that is, when one character compares as equal to combinations of other characters. For example, in German and some other languages “ß” is equal to “ss”. utf8_unicode_ci also supports contractions and ignorable characters. utf8_general_ci is a legacy collation that does not support expansions, contractions, or ignorable characters. It can make only one-to-one comparisons between characters.

引用自: http://dev.mysql.com/doc/refman/5.0/en/charset-unicode-sets.html

更详细的解释，请阅读 MySQL 论坛的以下帖子: http://forums.mysql.com/read.php?103,187048,188748

关于 utf8_bin:utf8_general_ci 和 utf8_unicode_ci 都执行不区分大小写的比较。相比之下，utf8_bin 区分大小写(还有其他区别)，因为它比较字符的二进制值。