kill psql connection to a database

foo.sql

-- show
SELECT * from pg_stat_activity;

-- Get the pid from the above query. Then:

-- kill
SELECT
    pg_terminate_backend(pid) -- this is your pid
FROM
    pg_stat_activity
WHERE
    -- don't kill my own connection!
    pid <> pg_backend_pid()
    -- don't kill the connections to other databases
    AND datname = '<dbname>';