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Re: Duplicate values being created
Posted by: Peter Brawley
Date: January 25, 2018 03:09PM

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.

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Re: Duplicate values being created
January 25, 2018 03:09PM

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