mysql - MariaDB/MySQL 中 utf8mb4_unicode_ci 和 utf8mb4_unicode_520_ci 排序规则的区别？

Question

我登录到 MariaDB/MySQL 并输入:

SHOW COLLATION;

我在可用排序规则中看到 utf8mb4_unicode_ci 和 utf8mb4_unicode_520_ci。这两种归类之间有什么区别，我们应该使用哪种？

Answer 1

好吧，您可以阅读文档中的差异。我不能告诉你应该使用什么，因为每个项目都不一样。

10.1.3 Collation Naming Conventions

MySQL collation names follow these conventions:

A collation name starts with the name of the character set with whichit is associated, followed by one or more suffixes indicating othercollation characteristics. For example, utf8_general_ci andlatin_swedish_ci are collations for the utf8 and latin1 charactersets, respectively.

A language-specific collation includes a language name. For example,utf8_turkish_ci and utf8_hungarian_ci sort characters for the utf8character set using the rules of Turkish and Hungarian, respectively.

Case sensitivity for sorting is indicated by _ci (case insensitive),_cs (case sensitive), or _bin (binary; character comparisons are based on character binary code values). For example, latin1_general_ci iscase insensitive, latin1_general_cs is case sensitive, and latin1_binuses binary code values.

For Unicode, collation names may include a version number to indicatethe version of the Unicode Collation Algorithm (UCA) on which thecollation is based. UCA-based collations without a version number inthe name use the version-4.0.0 UCA weight keys. For example:

utf8_unicode_ci (with no version named) is based on UCA 4.0.0 weightkeys >(http://www.unicode.org/Public/UCA/4.0.0/allkeys-4.0.0.txt).

utf8_unicode_520_ci is based on UCA 5.2.0 weight keys(http://www.unicode.org/Public/UCA/5.2.0/allkeys.txt).

For Unicode, the xxx_general_mysql500_ci collations preserve thepre-5.1.24 ordering of the original xxx_general_ci collations andpermit upgrades for tables created before MySQL 5.1.24. For moreinformation, see Section 2.11.3, “Checking Whether Tables or IndexesMust Be Rebuilt”, and Section 2.11.4, “Rebuilding or Repairing Tablesor Indexes”.

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