Returns 0 if str is the empty string.
Returns NULL if str is NULL.
ASCII() works for characters with numeric values from 0 to 255.
mysql> mysql> SELECT ASCII('2'); +------------+ | ASCII('2') | +------------+ | 50 | +------------+ 1 row in set (0.00 sec) mysql> SELECT ASCII(2); +----------+ | ASCII(2) | +----------+ | 50 | +----------+ 1 row in set (0.00 sec) mysql> mysql>