How to Calculate a Square Root in SQL

Problem:

You want to find the square root of a number.

Example:

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

Solution 1:

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

The result is:

Discussion:

To compute the square root of a number, 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 (imaginary 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.

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.