lacune trovando in date

Question

Qui di seguito è la mia tabella con i dati:

CREATE TABLE customer_wer (
    id_customer NUMBER, 
    name VARCHAR2(10), 
    surname VARCHAR2(20), 
    date_from DATE, 
    date_to DATE); 

--KAROLINA BIELAWSKA - GAP MAR APR 2000 and JUN JUL 2001 

INSERT INTO customer_wer VALUES (2, 'Karolina', 'Bielawska', '01-JAN-00', '28-MAR-00'); 
INSERT INTO customer_wer VALUES (2, 'Karolina', 'Bielawska', '01-APR-00', '30-JUN-00'); 
INSERT INTO customer_wer VALUES (2, 'Karolina', 'Bielawska', '01-JUL-00', '30-SEP-00'); 
INSERT INTO customer_wer VALUES (2, 'Karolina', 'Bielawska', '01-OCT-00', '31-DEC-00'); 
INSERT INTO customer_wer VALUES (2, 'Karolina', 'Bielawska', '01-JAN-01', '31-MAR-01'); 
INSERT INTO customer_wer VALUES (2, 'Karolina', 'Bielawska', '01-APR-01', '15-JUN-01'); 
INSERT INTO customer_wer VALUES (2, 'Karolina', 'Bielawska', '01-JUL-01', '30-SEP-01'); 
INSERT INTO customer_wer VALUES (2, 'Karolina', 'Bielawska', '01-OCT-01', '31-DEC-01'); 

--LUKASZ JAGIELLO - GAP JUN JUL 2000 

INSERT INTO customer_wer VALUES (3, 'Lukasz', 'Jagiello', '01-JAN-00', '31-MAR-00'); 
INSERT INTO customer_wer VALUES (3, 'Lukasz', 'Jagiello', '01-APR-00', '15-JUN-00'); 
INSERT INTO customer_wer VALUES (3, 'Lukasz', 'Jagiello', '01-JUL-00', '30-SEP-00'); 
INSERT INTO customer_wer VALUES (3, 'Lukasz', 'Jagiello', '01-OCT-00', '31-DEC-00'); 
INSERT INTO customer_wer VALUES (3, 'Lukasz', 'Jagiello', '01-JAN-01', '31-MAR-01'); 
INSERT INTO customer_wer VALUES (3, 'Lukasz', 'Jagiello', '01-APR-01', '30-JUN-01'); 
INSERT INTO customer_wer VALUES (3, 'Lukasz', 'Jagiello', '01-JUL-01', '30-SEP-01'); 
INSERT INTO customer_wer VALUES (3, 'Lukasz', 'Jagiello', '01-OCT-01', '31-DEC-01'); 

ho trovato lacune con sottostante selezionare:

SELECT date_from, date_to, id_customer, next_date 
    FROM 
    (SELECT k.*, 
      LEAD(date_from, 1) OVER (partition by id_customer order by date_from) AS next_date 
     FROM customer_wer k 
    ) 
WHERE date_to + 1 <> next_date AND date_to < '31-DEC-01' AND date_to < next_date; 

Vorrei sapere se è possibile avere gli stessi risultati con tabella di duplicazione. Non riesco a trovare la soluzione corretta. La mia selezione è di seguito:

SELECT COUNT(k.id_customer) 
    FROM customer_wer k 
    JOIN customer_wer w 
    ON k.id_customer = w.id_customer 
    WHERE (w.date_from < k.date_from AND w.date_to + 1 < k.date_from); 

Ci dovrebbe essere un ulteriore limite.

Answer 1

Questo self-join query di prodotto lo stesso risultato come la tua:

with data as (
    select rownum rn, x.* from customer_wer x 
    order by id_customer, date_from) 
select k.date_from, k.date_to, k.id_customer, w.date_from next_date 
    from data k 
    join data w on k.id_customer = w.id_customer and k.rn + 1 = w.rn 
    where k.date_to+1 < w.date_from 
    order by k.id_customer, k.date_from; 

e penso che si dovrebbe cambiare l'ordine nella vostra funzione analitica per:

OVER (partition by id_customer order by date_from)