sql >> Databasteknik >  >> RDS >> Mysql

sql drar en rad för nästa eller föregående rad i en aktuell rad

Det här är vad jag använder för att hitta tidigare/nästa poster. Vilken kolumn som helst i din tabell kan användas som sorteringskolumn, och inga kopplingar eller elaka hack krävs:

Nästa post (datum större än nuvarande post):

SELECT id, title, MIN(created) AS created_date
FROM photo
WHERE created >
  (SELECT created FROM photo WHERE id = '32kJ')
GROUP BY created
ORDER BY created ASC
LIMIT 1;

Föregående post (datum mindre än nuvarande post):

SELECT id, title, MAX(created) AS created_date
FROM photo
WHERE created <
  (SELECT created FROM photo WHERE id = '32kJ')
GROUP BY created
ORDER BY created DESC
LIMIT 1;

Exempel:

CREATE TABLE `photo` (
    `id` VARCHAR(5) NOT NULL,
    `title` VARCHAR(255) NOT NULL,
    `created` DATETIME NOT NULL,
    INDEX `created` (`created` ASC),
    PRIMARY KEY (`id`)
)
ENGINE = InnoDB;

INSERT INTO `photo` (`id`, `title`, `created`) VALUES ('XEi43', 'my family',       '2009-08-04');
INSERT INTO `photo` (`id`, `title`, `created`) VALUES ('dDls',  'friends group',   '2009-08-05');
INSERT INTO `photo` (`id`, `title`, `created`) VALUES ('32kJ',  'beautiful place', '2009-08-06');
INSERT INTO `photo` (`id`, `title`, `created`) VALUES ('EOIk',  'working late',    '2009-08-07');

SELECT * FROM photo ORDER BY created;
+-------+-----------------+---------------------+
| id    | title           | created             |
+-------+-----------------+---------------------+
| XEi43 | my family       | 2009-08-04 00:00:00 |
| dDls  | friends group   | 2009-08-05 00:00:00 |
| 32kJ  | beautiful place | 2009-08-06 00:00:00 |
| EOIk  | working late    | 2009-08-07 00:00:00 |
+-------+-----------------+---------------------+


SELECT id, title, MIN(created) AS next_date
FROM photo
WHERE created >
  (SELECT created FROM photo WHERE id = '32kJ')
GROUP BY created
ORDER BY created ASC
LIMIT 1;

+------+--------------+---------------------+
| id   | title        | next_date           |
+------+--------------+---------------------+
| EOIk | working late | 2009-08-07 00:00:00 |
+------+--------------+---------------------+

SELECT id, title, MAX(created) AS prev_date
FROM photo
WHERE created <
  (SELECT created FROM photo WHERE id = '32kJ')
GROUP BY created
ORDER BY created DESC
LIMIT 1;

+------+---------------+---------------------+
| id   | title         | prev_date           |
+------+---------------+---------------------+
| dDls | friends group | 2009-08-05 00:00:00 |
+------+---------------+---------------------+


  1. Generera INSERT-satser från SQLite-frågeresultat

  2. Kan inte hitta PostgreSQL-klientbiblioteket (libpq)

  3. MySQL många-till-många Välj

  4. LPAD med inledande nolla