MySQL:

ATAN2

Syntax:
ATAN(Y,X), ATAN2(Y,X)

Returns the arc tangent of the two variables X and Y. It is similar to
calculating the arc tangent of Y / X, except that the signs of both
arguments are used to determine the quadrant of the result.

Example

mysql> SELECT ATAN(-2,2);
-> -0.78539816339745
mysql> SELECT ATAN2(PI(),0);
-> 1.5707963267949

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