LN() Function in MySQL

LN() function : It is the function in MySQL is used to calculate the natural logarithm of a specific number with base e . The number must be greater than 0, otherwise it will return NULL. Syntax :

LN(X)

Parameter : LN() function accepts one parameter as mentioned above in the syntax and described below as follows. X – A number whose logarithm value with base e we want to calculate. It should be a positive number. Returns : It returns the natural logarithm of given number x with base e. Example-1 : The logarithm of the given number with base e using the LN() function.

SELECT LN(1000) AS Ln_Val ;

Output :

LN_VAL
6.907755278982137

Example-2 : The logarithm of 0 using LN() function.

SELECT LN(0) AS Ln_Val ;

Output :

LN_VAL
NULL

Example-3 : The LN function can also be used to find the logarithmic value with base e of a column data. To demonstrate create a table named Product.

CREATE TABLE Product(
Product_id INT AUTO_INCREMENT,  
Product_name VARCHAR(100) NOT NULL,
Buying_price DECIMAL(13, 2) NOT NULL,
Selling_price DECIMAL(13, 2) NOT NULL,
Service_grade Decimal(6, 2) NOT NULL,
PRIMARY KEY(Product_id)
);

Inserting into the Product table : Now inserting some data to the Product table –

INSERT INTO  
Product(Product_name, Buying_price, Selling_price, Service_grade)
VALUES
('Touring Bike', 20000.00, 30050.00, 4.17 ),
('Mountain Bike', 30005.50, 40000.56, 10.00 ),
('Road Bike', 10000.20, 21000.56, -3.59 ),
('Road Bicycle', 15200.50, 18000.00, -0.50 ),
('Racing Bicycle', 30500.50, 45000.00, 3.00) ;

Reading data from table : Showing all data in Product Table –

Select * from Product;

Output :

PRODUCT_ID	PRODUCT_NAME	BUYING_PRICE	SELLING_PRICE	SERVICE_GRADE
1	Touring Bike	20000.00	30050.00	4.17
2	Mountain Bike	30005.50	40000.56	10.00
3	Road Bike	10000.20	21000.56	-3.59
4	Road Bicycle	15200.50	18000.00	-0.50
5	Racing Bicycle	30500.50	45000.00	3.00

Now, we are going to find the logarithmic values with base e for all the records present in the Service_grade column.

Select Product_id, Product_name, Buying_price,  
Selling_price, Service_grade,
LN(Service_grade) AS GRADELOGN  
FROM Product;

Output :

PRODUCT_ID	PRODUCT_NAME	BUYING_PRICE	SELLING_PRICE	SERVICE_GRADE	GRADELOGN
1	Touring Bike	20000.00	30050.00	4.17	1.4279160358107101
2	Mountain Bike	30005.50	40000.56	10.00	2.302585092994046
3	Road Bike	10000.20	21000.56	-3.59	NULL
4	Road Bicycle	15200.50	18000.00	-0.50	NULL
5	Racing Bicycle	30500.50	45000.00	3.00	1.0986122886681098