mysql - MySQL 中的 utf8_general_ci 和 utf8_unicode_ci 有什么区别？

Question

一段时间以来，我一直使用 phpMyAdmin 来管理本地 MySQL 数据库。我开始接受的一件事是我的数据库的正确字符集。我已经确定 UTF-8 是兼容性最好的(因为我的 XHTML 模板作为 UTF-8 使用)但让我感到困惑的一件事是我在 phpMyAdmin 界面中看到的 UTF-8 的各种选项？

我隔离的两个是:

• utf8_general_ci
• utf8_unicode_ci

所以我的问题是:MySQL 中 utf8 的 general 和 unicode 变体有什么区别？ (我了解到 ci 是不区分大小写的简写)

在这件事上任何帮助将不胜感激。

Answer 1

来自MySQL manual on Unicode Character Sets :

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.

参见 further information and examples 的引用页.