Syntax:
INET6_NTOA(expr)

Given an IPv6 or IPv4 network address represented in numeric form as a
binary string, returns the string representation of the address as a
string in the connection character set. If the argument is not a valid
address, INET6_NTOA() returns NULL.

INET6_NTOA() has these properties:

o It does not use operating system functions to perform conversions,
  thus the output string is platform independent.

o The return string has a maximum length of 39 (4 x 8 + 7). Given this
  statement:

CREATE TABLE t AS SELECT INET6_NTOA(expr) AS c1;

  The resulting table would have this definition:

CREATE TABLE t (c1 VARCHAR(39) CHARACTER SET utf8 DEFAULT NULL);

o The return string uses lowercase letters for IPv6 addresses.

URL: https://dev.mysql.com/doc/refman/5.7/en/miscellaneous-functions.html

