How to Calculate a Square Root in SQL

Problem

You want to find the square root of a number in SQ:.

Example

You want to compute the square root of all numbers in the column number from the table data.

Solution

SELECT
  number,
  SQRT(number) AS square_root
FROM data;

The result is:

Discussion

To compute the square root of a number in SQL, use the SQRT() function. This function takes a number as its argument and returns the square root.

Note that there is no real square root from a negative number (complex numbers aren't supported) – hence the error.

Also, for most numbers (e.g., 2, 2.5, 3, 3.2 etc.) the square root is an irrational number – in the square_root column you won't see the exact results, only the first several digits of their decimal expansion.