Created
January 22, 2010 20:11
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Renumber the keys of MySQL table
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-- Let's say you had a table fruit | |
CREATE TABLE IF NOT EXISTS `fruit` ( | |
`id` int(11) NOT NULL auto_increment, | |
`blah` varchar(255) NOT NULL, | |
PRIMARY KEY (`id`) | |
); | |
-- Then you populate it, and delete some rows: | |
-- id, blah | |
-- 1, apple | |
-- 4, orange | |
-- 5, banana | |
-- Add a new column | |
ALTER TABLE `fruit` ADD `new_key` INT NOT NULL FIRST; | |
-- Move over the existing keys into the new key | |
UPDATE `fruit` set new_key = id; | |
-- Make alterations to the new_key by tightening up: | |
UPDATE `fruit` set new_key = new_key - 2 where new_key > 1; | |
-- Now you have: | |
-- new_key, id, blah | |
-- 1, 1, apple | |
-- 2, 4, orange | |
-- 3, 5, banana | |
-- Once you have it like you like it, do: | |
ALTER TABLE `fruit` DROP `id`; | |
ALTER TABLE `fruit` ADD PRIMARY KEY ( `new_key` ); | |
ALTER TABLE `fruit` CHANGE `new_key` `id` INT( 11 ) NOT NULL AUTO_INCREMENT | |
-- then: | |
-- id, blah | |
-- 1, apple | |
-- 2, orange | |
-- 3, banana |
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