Monday, December 10, 2007
How e-commerce sites display multiple versions of same item
I've noticed on Amazon that when there are multiple editions of a book, sometimes it is hard to see all of them, or they do not come up in what would be a preferred sequence. For a book, one probably wants to see the most recently published version first. That will, in many cases, be a paperback, sometimes with more material added, often at a lower price. Sometimes the original may be out of print.
Guaranteeing that various versions always appear in a reliable order would appear to be related to conventions in coding SQL statements (and maybe in setting up database indexes). Options like DISTINCT and ORDER BY and DESCENDING would need to be considered.
I've even seen this happen in a school system payroll system paying substitutes where there was some complexity in how multiple-part assignments were coded.
I explained how this issue plays out with my own self-published books here.