? ATN2 (or ATAN2) Function in SQL

The ATN2() function (called ATAN2() in most SQL dialects) returns the arctangent of two numbers — typically y and x coordinates — and computes the angle between the positive x-axis and the point (x, y) on a plane.

? Purpose

• Calculates the angle (in radians) from the origin to the point (x, y).

• Takes into account the signs of both inputs to determine the correct quadrant.

• Returns a value between -? and ?.

? Syntax

ATN2(y, x)

or in some databases:

ATAN2(y, x)

• y: The y-coordinate (numerator)

• x: The x-coordinate (denominator)

? Examples

1. Basic usage:

SELECT ATN2(1, 1) AS angle_radians;-- Returns approx 0.785398 (?/4 radians)

2. Angle in degrees:

SELECT ATN2(1, 1) * 180 / PI() AS angle_degrees;-- Returns approx 45 degrees

3. Different quadrant:

SELECT ATN2(-1, -1) * 180 / PI() AS angle_degrees;-- Returns approx -135 degrees (or 225 degrees if normalized)

? Use Cases

• Calculating direction or heading from coordinates.

• Used in GIS (Geographic Information Systems) or spatial computations.

• Computing angles when both x and y components are known.

?? Supported In

• SQL Server: ATN2(y, x)

• MySQL, PostgreSQL, Oracle: use ATAN2(y, x)

If you want, I can also show you how to use it with coordinate data or combine with other trigonometric functions!