Re: Duplicate values being created

[Peter Brawley]

Obviously if it's not a PK or unique key, nothing in the logic you've shown prevents value dupes. If the table has an auto_increment PK, use that for ordering. Otherwise implement logic to prevent duplicates, eg populate a table imgord( ord int unsigned primary key, used bool ), and in the insert transaction find the smallest imgord.ord for which used=0, lock it for update, set it=1, and use that value in ext_images.