How to reorder a primary key?

Question

I have a table of 5700 records. The primary key is an integer. Now I noticed that some values are missing. Like this:

100 data
101 data 
102 data
104 data
         


        

Answer 1

Another way, without truncating whole table:

-- Make Backup of original table's content
CREATE TABLE `orig_tbl_backup` SELECT * FROM `orig_tbl`;
-- Drop needed column. 
ALTER TABLE `orig_tbl` DROP `id`;
-- Re-create it
ALTER TABLE `orig_tbl` AUTO_INCREMENT = 1;
ALTER TABLE `orig_tbl` ADD `id` int UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY FIRST;