Syntax:
ORD(str)

If the leftmost character of the string str is a multibyte character,
returns the code for that character, calculated from the numeric values
of its constituent bytes using this formula:

  (1st byte code)
+ (2nd byte code * 256)
+ (3rd byte code * 256^2) ...

If the leftmost character is not a multibyte character, ORD() returns
the same value as the ASCII() function. The function returns NULL if
str is NULL.

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

