Creating a linked list or similar queue in MySQL?

Question

I have a table of items that need to be displayed in a certain order, but that order can be changed. Items can be added at the beginning, end, or in the middle, and items can be rearranged. How can I set up the table to keep track of that order in such a way that it's easy to modify but the list can also be fetched in order with a single query?

For example, I could have a "NEXT_ID" column to do it linked list-style, but then how would I run a SELECT query to get the rows in order of the NEXT_ID chain?

Apologies in advance for the super-obvious solution I'm probably missing.

Answer 1

I have this problem often, and I solved it with a simple solution : an extra column called Sort Order (or DisplayOrder, whatever floats your boat really) . This allows me the flexibility to use auto-generated, auto-incremented ID column and have a special pre-defined sort.

In my case, I need them to come out of the database with an alphabetical order except that some items like "Other" and "N/A" are always last.

ProdID ProdText SortOrder
2      "Anchovies"    1
3      "Rivet"        2
4      "N/A"          4
5      "Other"        3

SELECT ProdID, ProdText ORDER BY Sort Order