MySQL 5.6

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select version();

version()

5.6.51

create table visits (ip varbinary(16) not null primary key, number_of_visits int not null)
insert into visits values (INET6_ATON('127.0.0.1'),1) on duplicate key update number_of_visits=number_of_visits+1
select INET6_NTOA(ip), number_of_visits from visits

INET6_NTOA(ip)
number_of_visits

127.0.0.1
1

insert into visits values (INET6_ATON('127.0.0.1'),1) on duplicate key update number_of_visits=number_of_visits+1
select INET6_NTOA(ip), number_of_visits from visits

INET6_NTOA(ip)
number_of_visits

127.0.0.1
2