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MySQL 8.0 Reference Manual  / ...  / Character Sets, Collations, Unicode  / Unicode Support  /  The utf8mb3 Character Set (3-Byte UTF-8 Unicode Encoding)

12.9.2 The utf8mb3 Character Set (3-Byte UTF-8 Unicode Encoding)

Theutf8mb3 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 useutf8mb4 rather thanutf8mb3 (seeSection 12.9.1, “The utf8mb4 Character Set (4-Byte UTF-8 Unicode Encoding)”).

Exactly the same set of characters is available inutf8mb3 anducs2. That is, they have the samerepertoire.

Note

The recommended character set for MySQL isutf8mb4. All new applications should useutf8mb4.

Theutf8mb3 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.

Expectutf8mb3 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 usingutf8mb4 for new applications. For guidance in converting existing applications which use utfmb3, seeSection 12.9.8, “Converting Between 3-Byte and 4-Byte Unicode Character Sets”.

utf8mb3 can be used inCHARACTER SET clauses, andutf8mb3_collation_substring inCOLLATE clauses, wherecollation_substring isbin,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 ofutf8mb3 in statements were converted toutf8. In MySQL 8.0.30 and later, the reverse is true, so that in statements such asSHOW CREATE TABLE orSELECT CHARACTER_SET_NAME FROM INFORMATION_SCHEMA.COLUMNS orSELECT COLLATION_NAME FROM INFORMATION_SCHEMA.COLUMNS, users see the character set or collation name prefixed withutf8mb3 orutf8mb3_.

utf8mb3 is also valid (but deprecated) in contexts other thanCHARACTER 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, seeString Type Storage Requirements.