Motor MyISAM to udělá za vás -
Definice tabulky:
CREATE TABLE `sequence` (
`label` char(30) CHARACTER SET latin1 NOT NULL,
`id` mediumint(9) NOT NULL AUTO_INCREMENT,
PRIMARY KEY (`label`,`id`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8;
Naplnit tabulku:
INSERT INTO sequence VALUES ('a', NULL); -- add some 'a' labels
INSERT INTO sequence VALUES ('a', NULL);
INSERT INTO sequence VALUES ('a', NULL);
INSERT INTO sequence VALUES ('b', NULL); -- add another labels 'b'
INSERT INTO sequence VALUES ('b', NULL);
INSERT INTO sequence VALUES ('a', NULL); -- add some 'a' labels
INSERT INTO sequence VALUES ('a', NULL);
Zobrazit výsledek:
SELECT * FROM sequence;
+-------+----+
| label | id |
+-------+----+
| a | 1 |
| a | 2 |
| a | 3 |
| a | 4 |
| a | 5 |
| a | 6 |
| b | 1 |
| b | 2 |
+-------+----+