The utf8mb3 Character Set (3-Byte UTF-8 Unicode Encoding) The  utfmb4  character set has these characteristics: utf8mb4  contrasts with the  utf8mb3  character set, which supports only BMP characters and uses a maximum of three bytes per character: utf8mb4  is a superset of  utf8mb3 , so for an operation such as the following concatenation, the result has character set  utf8mb4  and the collation of  utf8mb4_col : Similarly, the following comparison in the  WHERE  clause works according to the collation of  utf8mb4_col : For information about data type storage as it relates to multibyte character sets, see String Type Storage Requirements. The  utf8mb3  character set has these characteristics: 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  utf8mb3  and  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. Note The  utf8mb3  character set is deprecated and you should expect it to be removed in a future MySQL release. Please use  utf8mb4  instead. Although  utf8  is currently an alias for  utf8mb3 , at some point  utf8  is expected to become a reference to  utf8mb4 . To avoid ambiguity about the meaning of  utf8 , consider specifying  utf8mb4  explicitly for character set references instead of  utf8 . utf8mb3  can be used in  CHARACTER SET  clauses, and  utf8mb3_ collation_substring  in 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’; SELECT * FROM utf8mb3_tbl, utf8mb4_tbl WHERE utf8mb3_tbl.utf8mb3_col = utf8mb4_tbl.utf8mb4_col; SELECT CONCAT(utf8mb3_col, utf8mb4_col); •Supports BMP and supplementary characters. •Requires a maximum of four bytes per multibyte character. •For a BMP character,  utf8mb4  and  utf8mb3  have identical storage characteristics: same code values, same encoding, same length. •For a supplementary character,  utf8mb4  requires four bytes to store it, whereas  utf8mb3  cannot store the character at all. When converting  utf8mb3  columns to  utf8mb4 , you need not worry about converting supplementary characters because there are none. •Supports BMP characters only (no support for supplementary characters) •Requires a maximum of three bytes per multibyte character. 10.9.2 The utf8mb3 Character Set (3-Byte UTF-8 Unicode Encoding) 1964