MySQL 5.7 Release Notes
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.
The ucs2 character set has these
characteristics:
Supports BMP characters only (no support for supplementary characters)
Uses a fixed-length 16-bit encoding and requires two bytes per character.