Identifiers are stored in mysql database
tables (user, db, and so
forth) using utf8, but identifiers can
contain only characters in the Basic Multilingual Plane (BMP).
Supplementary characters are not permitted in identifiers.
The ucs2, utf16,
utf16le, and utf32
character sets have the following restrictions:
They cannot be used as a client character set, which means
that they do not work for SET NAMES or
SET CHARACTER SET. (See
Connection Character Sets and Collations.)
It is currently not possible to use
LOAD DATA
INFILE to load data files that use these
character sets.
FULLTEXT indexes cannot be created on a
column that uses any of these character sets. However, you
can perform IN BOOLEAN MODE searches on
the column without an index.
The use of ENCRYPT() with
these character sets is not recommended because the
underlying system call expects a string terminated by a
zero byte.
The REGEXP and
RLIKE
operators work in byte-wise fashion, so they are not multibyte
safe and may produce unexpected results with multibyte
character sets. In addition, these operators compare
characters by their byte values and accented characters may
not compare as equal even if a given collation treats them as
equal.