SQL Server SQRT() Function

Summary: in this tutorial, you will learn how to use the SQL Server SQRT() function to calculate the square root of a number.

Introduction to the SQL Server SQRT() function

The SQRT() function is a useful mathematical function that allows you to calculate the square root of a number.

The following shows the syntax of the SQRT() function:

SQRT(number)Code language: SQL (Structured Query Language) (sql)

In this syntax, the number can be a float or any number that can be implicitly converted to a float. Also, it can be a numeric expression.

The SQRT() function returns the square root of the number with the type of float. It returns NULL if the number is NULL.

SQL Server SQRT() function examples

Let’s take some examples of using the SQRT() function.

1) Basic SQRT() function example

The following statement uses the SQRT() function to return the square root of 16:

SELECT SQRT(16) AS result;Code language: SQL (Structured Query Language) (sql)

Result:

result
------
4.0Code language: SQL (Structured Query Language) (sql)

The query returns 4.0 as the square root of 16.

2) Using SQRT() function to calculate distance

First, create a table called coordinates that stores the x and y-coordinates of points in two-dimensional space:

CREATE TABLE coordinates (
    id INT IDENTITY PRIMARY KEY,
    x NUMERIC,
    y NUMERIC,
    UNIQUE (x, y)
);Code language: SQL (Structured Query Language) (sql)

Second, insert some rows into the coordinates table:

INSERT INTO coordinates (x, y) 
VALUES
    (2, 3),
    (-1, 7),
    (0, 0),
    (9, -5),
    (-2.5, 3.5);Code language: SQL (Structured Query Language) (sql)

Third, retrieve data from the coordinates table:

SELECT
  id,
  x,
  y
FROM
  coordinates;Code language: SQL (Structured Query Language) (sql)

Output:

id | x  | y
---+----+----
5  | -3 | 4
2  | -1 | 7
3  | 0  | 0
1  | 2  | 3
4  | 9  | -5
(5 rows)Code language: plaintext (plaintext)

Finally, calculate the distance of each point from the origin (0,0) using the SQRT() function:

SELECT
  SQRT(x * x + y * y) AS distance
FROM
  coordinates;Code language: SQL (Structured Query Language) (sql)

Output:

distance
--------------------
5.0
7.0710678118654755
0.0
3.605551275463989
10.295630140987
(5 rows)Code language: plaintext (plaintext)

To make the result more readable, you can use the ROUND() function to round the distances to numbers with two precisions and the CAST() function to cast them to a number with two decimal places.

SELECT
  CAST(ROUND(SQRT(x * x + y * y), 2) AS DEC(5, 2)) AS distance
FROM
  coordinates;Code language: SQL (Structured Query Language) (sql)

Output:

distance
--------
5.00
7.07
0.00
3.61
10.30
(5 rows)Code language: plaintext (plaintext)

Summary

• Use the SQL Server SQRT() function to calculate the square root of a number.