MariaDB 10.5

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select version();

version()

10.5.12-MariaDB

create table visits (ip inet6 not null primary key, number_of_visits int not null)
insert into visits values ('::127.0.0.1',1) on duplicate key update number_of_visits=number_of_visits+1
select * from visits

ip
number_of_visits

::127.0.0.1
1

insert into visits values ('::127.0.0.1',1) on duplicate key update number_of_visits=number_of_visits+1
select * from visits

ip
number_of_visits

::127.0.0.1
2