str1 corresponds to bit 0, str2 to bit 1, and so on.
NULL values in str1, str2, ... are not appended to the result.
mysql> mysql> SELECT MAKE_SET(1,'a','b','c'); +-------------------------+ | MAKE_SET(1,'a','b','c') | +-------------------------+ | a | +-------------------------+ 1 row in set (0.00 sec) mysql>