SQL LOG()
This function was introduced
within the release of SQL Server 2005. This function is used to calculate the
natural logarithm of a number in SQL. In a very simple manner, we can say that
the LOG function computes the logarithm of an expression. It plays a very
important role in the data analytics.
Syntax
We can use this function by
using below syntax
LOG (Float Expression
[, Base ] )
Base
Optional
integer argument that sets the base for the logarithm. The base by which to
compute the logarithm. When you do not specify a value, the function computes
the natural logarithm of the expression by using e for the base where e is
equal to 2.718281828459.
Float Expression
A numeric
expression which is greater than zero. When the value is equal to or less
than zero, LOG returns an NA value.
Return Types: The important thing
is that it always return float type output.
Remarks: By default, LOG()
returns the natural logarithm. User
can change the base of the logarithm to another value using the optional base
parameter.
The natural
logarithm of the exponential of a number is the number itself: LOG( EXP( n ) ) = n. And the
exponential of the natural logarithm of a number is the number itself:
EXP( LOG( n
) ) = n.

Calculating
the logarithm
You can easily calculate the
log for the specified float expression as given below:
 declare float variable and set value
Declare @inpFloat float=10.24
 declare int variable and set value
Declare @inpInt int=10
 declare decimal variable and set value
Declare @inpDecimal int=10.24
 select value from the log function
SELECT LOG(@inpFloat) as 'LOG Value from Float',
LOG(@inpInt) as
'LOG Value from Int',
LOG(@inpDecimal) as 'LOG Value from Decimal'
 declare base
Declare @base int=2
 select value from the log function
SELECT LOG(@inpFloat, @base ) as 'LOG Value from Float',
LOG(@inpInt, @base) as 'LOG Value from Int',
LOG(@inpDecimal, @base) as 'LOG Value from Decimal'

Now, we can see that log
function returns two results. One is without base value and another one is with
base value.
Conclusion
As we already know that this
function plays important role in the data analytics calculations. Apart from
this; logarithm is used by navigators, scientists, engineers, and others to
perform computations more easily. In publickey cryptography application,
discrete logarithm is used to generate keys.
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