The SQL LOG function is a SQL Mathematical function which calculates the natural logarithmic value of given float value. The syntax of the SQL Server LOG Function is as shown below:
SELECT LOG (Float_Expression, base) FROM [Source]
Base: This is an optional argument. If you omit this argument, the SQL LOG function will consider the default e as logarithm base. However, you can change the base value as per your requirement. The value of e is approximately equal to 2.71828
SQL LOG Function Example 1
The SQL Logarithmic Function is used to calculate the logarithmic value of a given number with the specified base value. In this example, We are going to check the same with different data and display the output
DECLARE @i float SET @i = 10 SELECT LOG(@i)AS [LOG Result 1] -- Calculating LOG directly SELECT LOG(1) AS [LOG Result 2] SELECT LOG(96) AS [LOG Result 3] SELECT LOG(10.90 + 15.10 - 22.50 + 1.50) AS [LOG Result 4] -- Calculating LOG with two arguments SELECT LOG(10, 4) AS [LOG Result 5] SELECT LOG((10.90 + 15.10 - 22.50 + 1.50), 8) AS [LOG Result 6]
OUTPUT
ANALYSIS
Within this log function example query, we are calculating the logarithmic value of @i base e (It means LOG(10, e)).
SELECT LOG(@i)AS [LOG Result 1]
In the below statement, We used LOG function directly on the float values
SELECT LOG(1) AS [LOG Result 2] SELECT LOG(96) AS [LOG Result 3] SELECT LOG(10.90 + 15.10 - 22.50 + 1.50) AS [LOG Result 4]
In the next statement, We used the LOG Function with two arguments (float and base value). It means the logarithmic value of 10 bases 4.
SELECT LOG(10, 4) AS [LOG Result 5]
SQL Logarithmic Function Example 2
In this example, We are going to calculate the logarithmic value of all the records present in the [StandardCost] and [Tax Amount] using LOG Function.
SELECT [EnglishProductName] ,[Color] ,[StandardCost] ,LOG([StandardCost], 8) AS [Cost_Log result] ,[ListPrice] ,[DealerPrice] ,[SalesAmount] ,[TaxAmt] ,LOG([TaxAmt]) AS [Tax_Log result] FROM [SQL Tutorial].[dbo].[Prod Sales]
OUTPUT