How to limit the number of connections per DB in the PostgreSQL?

How to limit the number of connections per DB in the PostgreSQL?

alter database my_db connection limit 10;

How to check the limit on the number of connections per DB in the PostgreSQL?

select datconnlimit from pg_database where datname='my_db';

How to reset (i.e. return to default) the limit on the number of connections per DB in the PostgreSQL?

alter database my_db connection limit -1;