If called with two parameters, this function returns the logarithm of X for an arbitrary base B.
mysql> mysql> SELECT LOG(2,65536); +--------------+ | LOG(2,65536) | +--------------+ | 16 | +--------------+ 1 row in set (0.00 sec) mysql> SELECT LOG(10,100); +-------------+ | LOG(10,100) | +-------------+ | 2 | +-------------+ 1 row in set (0.01 sec) mysql> LOG(B,X) is equivalent to LOG(X) / LOG(B). mysql>
mysql> mysql> SELECT LOG2(65536); +-------------+ | LOG2(65536) | +-------------+ | 16 | +-------------+ 1 row in set (0.00 sec) mysql> mysql> SELECT LOG2(-100); +------------+ | LOG2(-100) | +------------+ | NULL | +------------+ 1 row in set (0.00 sec) mysql>