SQL Server LOG() Function

Return the natural logarithm of 2:

SELECT LOG(2);

Definition and Usage

The LOG() function returns the natural logarithm of a specified number, or the logarithm of the number to the specified base.

From SQL Server 2012, you can also change the base of the logarithm to another value by using the optional base parameter.

Note: Also look at the EXP() function.

LOG(number, base) -- Syntax for SQL Server

OR:

LOG(number) -- Syntax for Azure SQL Database, Azure SQL Data Warehouse, Parallel Data Warehouse

Parameter	Description
number	Required. The number to return the natural logarithm of. Must be greater than 0
base	Optional. The base the natural logarithm is to be calculated with. Must be greater than 1

Works in:	SQL Server (starting with 2008), Azure SQL Database, Azure SQL Data Warehouse, Parallel Data Warehouse

Return the natural logarithm of 2 to a specified base (4):

SELECT LOG(2, 4);