MySQL uzyskać brakujące identyfikatory z tabeli

Question

mam tej tabeli w MySQL, na przykład:

ID | Name 
1 | Bob 
4 | Adam 
6 | Someguy 

Jeśli zauważysz, nie ma numeru ID (2, 3 i 5).

Jak napisać zapytanie, aby MySQL odpowiadało tylko na brakujące identyfikatory, w tym przypadku: "2,3,5"?

Answer 1

SELECT a.id+1 AS start, MIN(b.id) - 1 AS end 
    FROM testtable AS a, testtable AS b 
    WHERE a.id < b.id 
    GROUP BY a.id 
    HAVING start < MIN(b.id) 

Nadzieja ten link pomaga również http://www.codediesel.com/mysql/sequence-gaps-in-mysql/

Answer 2

Bardziej zapytania skuteczny:

SELECT (t1.id + 1) as gap_starts_at, 
     (SELECT MIN(t3.id) -1 FROM my_table t3 WHERE t3.id > t1.id) as gap_ends_at 
FROM my_table t1 
WHERE NOT EXISTS (SELECT t2.id FROM my_table t2 WHERE t2.id = t1.id + 1) 
HAVING gap_ends_at IS NOT NULL 

Answer 3

Przede zapytań dadzą dwie kolumny, dzięki czemu można spróbować uzyskać brakujące numery w jednej kolumnie

select start from 
(SELECT a.id+1 AS start, MIN(b.id) - 1 AS end 
    FROM sequence AS a, sequence AS b 
    WHERE a.id < b.id 
    GROUP BY a.id 
    HAVING start < MIN(b.id)) b 
UNION 
select c.end from (SELECT a.id+1 AS start, MIN(b.id) - 1 AS end 
    FROM sequence AS a, sequence AS b 
    WHERE a.id < b.id 
    GROUP BY a.id 
    HAVING start < MIN(b.id)) c order by start; 

Answer 4

Aby dodać trochę do odpowiedzi Iwana, są numery Pokazuje wersję brakuje na początku, jeśli 1 nie istnieje:

SELECT 1 as gap_starts_at, 
     (SELECT MIN(t4.id) -1 FROM testtable t4 WHERE t4.id > 1) as gap_ends_at 
FROM testtable t5 
WHERE NOT EXISTS (SELECT t6.id FROM testtable t6 WHERE t6.id = 1) 
HAVING gap_ends_at IS NOT NULL limit 1 
UNION 
SELECT (t1.id + 1) as gap_starts_at, 
     (SELECT MIN(t3.id) -1 FROM testtable t3 WHERE t3.id > t1.id) as gap_ends_at 
FROM testtable t1 
WHERE NOT EXISTS (SELECT t2.id FROM testtable t2 WHERE t2.id = t1.id + 1) 
HAVING gap_ends_at IS NOT NULL;