create table appointments
(
    id                  serial   not null constraint appointments_pkey           primary key,
    patient_id          varchar(255)                                   not null,
    date                timestamp(0)  not null
);

SELECT
        (
                    SELECT MIN(ap.date) FROM appointments ap
                    WHERE ap.date >= NOW() AND ap.patient_id = '1'
        ) AS next,
        (
                    SELECT MAX(ap.date) FROM appointments ap
                    WHERE ap.date < NOW() AND ap.patient_id = '1'
        ) AS last