12.11 字符集的限制
-
Identifiers are stored in
mysql
database tables (user
,db
, and so forth) usingutf8mb3
, but identifiers can contain only characters in the Basic Multilingual Plane (BMP). Supplementary characters are not permitted in identifiers. -
The
ucs2
,utf16
,utf16le
, andutf32
character sets have the following restrictions:-
None of them can be used as the client character set. See Impermissible Client Character Sets.
-
It is currently not possible to use
LOAD DATA
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 performIN BOOLEAN MODE
searches on the column without an index.
-
-
The
REGEXP
andRLIKE
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.