Syntax:
PI()

Returns the value of π (pi). The default number of decimal places
displayed is seven, but MySQL uses the full double-precision value
internally.

Because the return value of this function is a double-precision value,
its exact representation may vary between platforms or implementations.
This also applies to any expressions making use of PI(). See
https://dev.mysql.com/doc/refman/8.0/en/floating-point-types.html.

URL: https://dev.mysql.com/doc/refman/8.0/en/mathematical-functions.html

