10.9.2 The utf8mb3 Character Set (3-Byte UTF-8 Unicode Encoding)
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 10.9.1, “The utf8mb4 Character Set (4-Byte UTF-8 Unicode Encoding)”).
Exactly the same set of characters is available in
ucs2. That is, they have the same repertoire.
utf8 is an alias for
utf8mb3; the character limit is implicit, rather than explicit in the name.
utf8mb3 can be used in
CHARACTER SET clauses, and
COLLATE clauses, where
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 utf8) COLLATE utf8_czech_ci;
MySQL immediately converts instances of
utf8mb3 in statements to
utf8, so 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 will see the name
utf8mb3 is also valid in contexts other than
CHARACTER SET clauses. For example:
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.