The utf8mb3
character set has these
characteristics:
Supports BMP characters only (no support for supplementary characters)
Requires a maximum of three bytes per multibyte character.
Applications that use UTF-8 data but require supplementary
character support should use utf8mb4
rather
than utf8mb3
(see
Section 12.9.1, “The utf8mb4 Character Set (4-Byte UTF-8 Unicode Encoding)”).
Exactly the same set of characters is available in
utf8mb3
and ucs2
. That is,
they have the same
repertoire.
The recommended character set for MySQL is
utf8mb4
. All new applications should use
utf8mb4
.
The utf8mb3
character set is deprecated.
utf8mb3
remains supported for the lifetimes
of the MySQL 8.0.x and following LTS release series, as well
as in MySQL 8.0.
Expect utf8mb3
to be removed in a future
major release of MySQL.
Since changing character sets can be a complex and
time-consuming task, you should begin to prepare for this
change now by using utf8mb4
for new
applications. For guidance in converting existing applications
which use utfmb3, see
Section 12.9.8, “Converting Between 3-Byte and 4-Byte Unicode Character Sets”.
utf8mb3
can be used in CHARACTER
SET
clauses, and
utf8mb3_
in collation_substring
COLLATE
clauses, where
collation_substring
is
bin
, czech_ci
,
danish_ci
, esperanto_ci
,
estonian_ci
, and so forth. For example:
CREATE TABLE t (s1 CHAR(1)) CHARACTER SET utf8mb3;
SELECT * FROM t WHERE s1 COLLATE utf8mb3_general_ci = 'x';
DECLARE x VARCHAR(5) CHARACTER SET utf8mb3 COLLATE utf8mb3_danish_ci;
SELECT CAST('a' AS CHAR CHARACTER SET utf8mb4) COLLATE utf8mb4_czech_ci;
Prior to MySQL 8.0.29, instances of utf8mb3
in statements were converted to utf8
. In
MySQL 8.0.30 and later, the reverse is true, so that in
statements such as SHOW CREATE TABLE
or
SELECT CHARACTER_SET_NAME FROM
INFORMATION_SCHEMA.COLUMNS
or SELECT
COLLATION_NAME FROM INFORMATION_SCHEMA.COLUMNS
, users
see the character set or collation name prefixed with
utf8mb3
or utf8mb3_
.
utf8mb3
is also valid (but deprecated) in
contexts other than CHARACTER SET
clauses.
For example:
mysqld --character-set-server=utf8mb3
SET NAMES 'utf8mb3'; /* and other SET statements that have similar effect */
SELECT _utf8mb3 'a';
For information about data type storage as it relates to multibyte character sets, see String Type Storage Requirements.