PI() function in MySQL

PI() function in MySQL is used to return the Pi value. The default number of decimal places displayed is seven, but MySQL uses the full double-precision value internally.

Syntax :

PI()

Parameter :
This method does not accept any parameter.

Returns :
It returns the Pi value i.e. 3.141593.

Example-1 :
Returning the default value of Pi using PI Function.

SELECT PI() AS DefaultPiValue;

Output :

Example-2 :

Returning the value of Pi up to 18 decimal places using PI Function .  

SELECT PI()+0.000000000000000000 
AS PiValue;

Output :

Example-3 :
Using PI Function to calculate the area and perimeter of all circles in a column. To demonstrate, let us create a table named Circle.

CREATE TABLE Circle(
Circle_id INT AUTO_INCREMENT,  
Radius DECIMAL(10, 3) NOT NULL,
PRIMARY KEY(Circle_id )
);

Now, insert some data to the Circle table.

INSERT INTO Circle(Radius )
VALUES
(2 ),(3),(10 ),(12.5 ),(6.80),
(4.60 ),(6),(20),(25) ;

So, the Circle Table is as follows.

SELECT * FROM Circle;

Now, we will calculate the area and perimeter of every circle using PI function.

SELECT Circle_id, Radius,
PI() * Radius * Radius  AS Area,
2 * PI() * Radius AS Perimeter
FROM Circle;

Output :