Regular Expressions | REGEXP_INSTR(’??b’, ’b’) | +--------------------------+ | 5 | +--------------------------+ 1 row in set (0.00 sec) mysql>  SELECT REGEXP_INSTR(’ 㳟 bxxx’, ’b’, 4); +--------------------------------+ | REGEXP_INSTR(’??bxxx’, ’b’, 4) | +--------------------------------+ | 5 | +--------------------------------+ 1 row in set (0.00 sec) mysql>  SELECT REGEXP_INSTR(’ бж b’, ’b’); +----------------------------+ | REGEXP_INSTR(’ бж b’, ’b’) | +----------------------------+ | 3 | +----------------------------+ 1 row in set (0.00 sec) mysql>  SELECT REGEXP_INSTR(’ עב b’, ’b’); +----------------------------+ | REGEXP_INSTR(’ עב b’, ’b’) | +----------------------------+ | 3 | +----------------------------+ 1 row in set (0.00 sec) mysql>  SELECT REGEXP_INSTR(’µå 周 ç б ’, ’ 周 ’); +------------------------------------+ | REGEXP_INSTR(’µå 周 ç б ’, ’ 周 ’) | +------------------------------------+ | 3 | +------------------------------------+ 1 row in set (0.00 sec) mysql>  SELECT REGEXP_SUBSTR(’ 周周周周 ’, ’.*’, 2); +----------------------------------------+ | REGEXP_SUBSTR(’ 周周周周 ’, ’.*’, 2) | +----------------------------------------+ |  周周周 | +----------------------------------------+ 1 row in set (0.00 sec) mysql>  SELECT REGEXP_SUBSTR(’ 㳟 ’, ’.*’, 2); +--------------------------------+ | REGEXP_SUBSTR(’????’, ’.*’, 2) | +--------------------------------+ | ? 㳟揘㳟揘㳟揘 | 2199 Emoji, such as the “sushi”  character  㳟  (U+1F363) used in the first two examples, are not included in the Basic Multilingual Plane, but rather in Unicode’s Supplementary Multilingual Plane. Another issue can arise with emoji and other 4-byte characters when  REGEXP_SUBSTR()  or a similar function begins searching in the middle of a character. Each of the two statements in the following example starts from the second 2-byte position in the first argument. The first statement works on a string consisting solely of 2-byte (BMP) characters. The second statement contains 4-byte characters which are incorrectly interpreted in the result because the first two bytes are stripped off and so the remainder of the character data is misaligned. Characters within the Unicode Basic Multilingual Plane, which includes characters used by most modern languages, are safe in this regard: