MySQL LOG() function

In this context, we will learn how we can use the MySQL LOG () function with proper syntax and good examples.

Introduction of MySQL LOG() function

The LOG() function in MySQL is used to calculate the natural logarithm of a specific number. The number must be >0; Otherwise, it will return NULL.

Syntax of the MySQL LOG() function

The syntax of the MySQL LOG() function is given as follows:

LOG(Y) 

Parameters or arguments used in MySQL LOG() function:

Only one parameter is accepted by the LOG() function in MySQL, which is given as follows:

Y: It is the number that we want to calculate the logarithm of the number. It should be a positive number.

Returns: It will return the natural logarithm of the given number Y.

Application used for LOG() function:

The LOG() function can be used in the given below MySQL versions:

• MySQL 5.7
• MySQL 5.6
• MySQL 5.5
• MySQL 5.1
• MySQL 5.0
• MySQL 4.1
• MySQL 4.0
• MySQL 3.23

Examples of MySQL LOG() function:

Now, we will look into some examples of MySQL LOG functions.

Example-1 :

Here, we will find the logarithm of the given number using the LOG() function in MySQL.

SELECT LOG( 5 ) AS LOG_Val ;

Output :

LOG_VAL
1.6094379124341003
1 row in set (0.00 sec)

Example-2 :

Here, we will find the logarithm of 0 using the LOG() function in MySQL.

SELECT LOG(0) AS LOG_Val ;

Output :

LOG_VAL
NULL
1 row in set (0.00 sec)

Example-3 :

When we require to find the logarithmic value of column data, then we can take the help of the LOG function. For demonstration, we have created a table named commodity.

CREATE TABLE Commodity(
    Commodity_id INT AUTO_INCREMENT,
    Commodity_name VARCHAR(100) NOT NULL,
    Purchasing_price DECIMAL(13, 2) NOT NULL,
    Selling_price DECIMAL(13, 2) NOT NULL,
    Service_grade Decimal(6, 2) NOT NULL,
    PRIMARY KEY(Commodity_id)
);

After that, we will insert some data into the Commodity table:

INSERT INTO
    Commodity(Commodity_name, Purchasing_price, Selling_price, Service_grade)
VALUES
    ('Touring Bike,' 2019.00, 3009.6, 0.89 ),
    ('Mountain Bike,' 3019.50, 4000.56, 1.00 ),
    ('Road Bike,' 1019.20, 2000.56, -0.89 ),
    ('Road Bicycle,' 1019.50, 1500.56, -1.50 ),
    ('Racing Bicycle,' 3019.50, 4000.56, 2.00) ;

Now, we can view the table using the following query:

mysql> Select * from Commodity;

Commodity_id	Commodity_name	Purchasing_price	Selling_price	Service_grade
1	Touring Bike	2019.00	3009.60	0.89
2	Mountain Bike	3019.50	4000.56	1.00
3	Road Bike	1019.20	2000.56	-0.89
4	Road Bicycle	1019.50	1500.56	-1.50
5	Racing Bicycle	3019.50	4000.56	2.00

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

Select Commodity_id,  
 Commodity_name,  
 Purchasing_price,  
 Selling_price,  
 Service_grade,
 LOG(Service_grade) AS GRADELOG  
 FROM Commodity;

The Output is:

Commodity_id	Commodity_name	Purchasing_price	Selling_price	Service_grade	GRADELOG
1	Touring Bike	2019.00	3009.60	0.89	-0.11653381625595151
2	Mountain Bike	3019.50	4000.56	1.00	0
3	Road Bike	1019.20	2000.56	-0.89	NULL
4	Road Bicycle	1019.50	1500.56	-1.50	NULL
5	Racing Bicycle	3019.50	4000.56	2.00	0.6931471805599453

Summary:

In this context, we have learned how we can use the MySQL LOG() function to find the LOG values from given arguments respectively.