# How to Calculate a Square Root in SQL

Database:

Operators:

Table of Contents

## 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**

number |
---|

9 |

2 |

1 |

0.25 |

0 |

-4 |

## Solution:

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

The result is:

number | square_root |
---|---|

9 | 3 |

2 | 1.4142135623731 |

1 | 1 |

0.25 | 0.5 |

0 | 0 |

-4 | error |

## 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.