SQL - PI() Function

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SQL PI() function is a mathematics function in the SQL that return the value of π (pi).

The π is a mathematical constant that is the ratio of a circumference of a circle to its diameter, which is approximately equal to 3.14159.... It is an irrational number, which signifies that it cannot be expressed exactly as a ratio of two integers, rather than it is expressed in fraction i.e. 22/7 which is commonly used to express it.

Syntax

Following is the syntax of the PI() function −

SELECT PI() AS alias_name;

Example

In the following example, we are getting the PI value by using the PI function.

Following is the query −

SELECT PI() AS pi_value;

Output

Following is the output of the above SQL query −

+-----------------+
|        pi_value |
+-----------------+
| 3.14159265358979|
+-----------------+

Example

In the following example, we are using the ceiling() function along with pi() to display the pi value as an integer value.

Following is the SQL query −

SELECT CEILING(PI()) AS PI_VALUE;

Output

Following is the output of the above SQL query −

+----------+
| PI_VALUE |
+----------+
|        4 |
+----------+

Example

In the following example, we are using the round() function along with pi() to display the pi value as only two decimal places.

Following is the SQL query −

SELECT ROUND(PI(), 2) AS PI_VALUE;

Output

Following is the output of the above SQL query −

+----------+
| PI_VALUE |
+----------+
|      3.14|
+----------+

Example

In the following example, we are creating a table that has only one column named radius. And with the help of the radius, we are getting the area of the circle.

Let’s create a table named Test −

CREATE TABLE Test (radius INT);

Let’s insert r data into table −

INSERT INTO Test VALUES(20),(30),(40);

Let’s fetch the table details.

SELECT * FROM Test;

Following is the Test table −

+--------+
| radius |
+--------+
|     20 |
|     30 |
|     40 |
+--------+

Following is the query to calculate the area of the given radius −

SELECT
   radius, PI()*POWER(radius, 2) as Area
   FROM Test;

Output

Following is the output of the above SQL query −

+--------+--------------------+
| radius | Area               |
+--------+--------------------+
|     20 | 1256.6370614359173 |
|     30 | 2827.4333882308138 |
|     40 |  5026.548245743669 |
+--------+--------------------+