How to Use SQRT Function in MySQL: Syntax and Examples

In MySQL, you use the SQRT() function to calculate the square root of a number. Simply pass the number or column name inside the parentheses like SQRT(16), which returns 4.

Syntax

The SQRT() function takes one numeric argument and returns its square root. If the argument is negative, the function returns NULL.

• SQRT(number): Calculates the square root of number.

sql

SELECT SQRT(number) AS square_root FROM your_table;

Example

This example shows how to calculate the square root of a fixed number and a column value in a table.

sql

SELECT SQRT(25) AS sqrt_of_25;

-- Assuming a table named 'numbers' with a column 'value'
SELECT value, SQRT(value) AS sqrt_value FROM numbers;

Output

sqrt_of_25
5.0

value | sqrt_value
----- | ----------
16    | 4.0
9     | 3.0
25    | 5.0

Common Pitfalls

Common mistakes when using SQRT() include:

• Passing a negative number, which returns NULL because square root of negative numbers is not defined in real numbers.
• Using non-numeric data types, which can cause errors or unexpected results.

Always ensure the input is a non-negative number.

sql

SELECT SQRT(-9) AS invalid_sqrt; -- Returns NULL

-- Correct usage:
SELECT SQRT(9) AS valid_sqrt; -- Returns 3

Output

invalid_sqrt
NULL

valid_sqrt
3.0

Quick Reference

Function	Description	Example	Result
SQRT(number)	Returns square root of number	SQRT(16)	4.0
SQRT(0)	Square root of zero	SQRT(0)	0.0
SQRT(-1)	Negative input returns NULL	SQRT(-1)	NULL

Key Takeaways

Use SQRT(number) to get the square root of a non-negative number in MySQL.

SQRT returns NULL for negative inputs because square roots of negative numbers are not real.

Ensure the input to SQRT is numeric and non-negative to avoid errors or NULL results.

You can use SQRT on both fixed numbers and numeric columns in tables.