The base must be greater than 2 and less than 36 i.e. the lower limit of a base is 2 and the upper limit is 36. It is applied to both from_base and to_base values. If in case we provide out of limit values of the base then MySQL returns NULL as the output. Following example will demonstrate it −
Example
mysql> Select CONV(10,10,38); +----------------+ | CONV(10,10,38) | +----------------+ | NULL | +----------------+ 1 row in set (0.00 sec) mysql> Select CONV(10,72,2); +---------------+ | CONV(10,72,2) | +---------------+ | NULL | +---------------+ 1 row in set (0.00 sec) mysql> Select CONV(10,10,1); +---------------+ | CONV(10,10,1) | +---------------+ | NULL | +---------------+ 1 row in set (0.00 sec)