MySQL 8.4 Release Notes
Note
ucs2 字符集已被弃用；预计将在未来的 MySQL 版本中移除。你应该改用 utf8mb4。The ucs2 character set is deprecated;
expect it to be removed in a future MySQL release. You should
use utf8mb4 instead.
在 UCS-2 中，每个字符由一个 2 字节的 Unicode 代码表示，最高有效字节在前。例如：LATIN CAPITAL LETTER A 的代码是 0x0041，它存储为 2 字节序列：0x00 0x41。CYRILLIC SMALL LETTER
YERU（Unicode 0x044B）存储为 2 字节序列：0x04 0x4B。有关 Unicode 字符及其代码，请参考 Unicode 联盟网站。In UCS-2, every character is represented by a 2-byte Unicode
code with the most significant byte first. For example:
LATIN CAPITAL LETTER A has the code
0x0041 and it is stored as a 2-byte sequence:
0x00 0x41. CYRILLIC SMALL LETTER
YERU (Unicode 0x044B) is stored as
a 2-byte sequence: 0x04 0x4B. For Unicode
characters and their codes, please refer to the
Unicode Consortium
website.
ucs2 字符集具有以下特性：The ucs2 character set has these
characteristics:
仅支持 BMP 字符（不支持补充字符）Supports BMP characters only (no support for supplementary characters)
使用固定长度的 16 位编码，每个字符需要两个字节。Uses a fixed-length 16-bit encoding and requires two bytes per character.