sub connect {
    return DBI->connect(
        "DBI:mysql:".join(';',
            "database=$sql_database",
            "host=$sql_host",
            "port=$sql_port",
        ),
        $username, $password,
        {
            RaiseError => 0,
            AutoCommit => 1,
        },
    );
};

my $dbh = connect()
   or die("Can't connect: $DBI::errstr\n");