DOUBLE log2(DOUBLE x) Returns the natural logarithm of x to base 2.
mysql> select log2(1); +-----------+ | log2(1.0) | +-----------+ | 0 | +-----------+ mysql> select log2(2); +-----------+ | log2(2.0) | +-----------+ | 1 | +-----------+ mysql> select log2(10); +--------------------+ | log2(10.0) | +--------------------+ | 3.3219280948873622 | +--------------------+
LOG2