Re: How to generate the order if you know the next item for each item?
| От | Tony Shelver |
|---|---|
| Тема | Re: How to generate the order if you know the next item for each item? |
| Дата | |
| Msg-id | CAG0dhZCWoSGorUqCidfM9P_nz6yzx9W1zYmjt-0j9oo7Hjv8gQ@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: How to generate the order if you know the next item for each item? ("David G. Johnston" <david.g.johnston@gmail.com>) |
| Ответы |
Re: How to generate the order if you know the next item for each item?
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| Список | pgsql-sql |
We have some ordered processing that we need to do that can involve reading through 10s of thousands of records, with a lot of conditional processing. We use functions almost exclusively for this, returning a table of results.
On Tue, 3 Aug 2021 at 18:22, David G. Johnston <david.g.johnston@gmail.com> wrote:
On Tue, Aug 3, 2021 at 8:40 AM Rockdale Green <rockdale.green@gmail.com> wrote:can I do it in one query?Yes.It might be just very simple and I have tried but somehow I am blocked.The feature you need is a recursive CTE (WITH RECURSIVE clause). It requires an initial row (which in this case is task 3, the only task that doesn't appear as a task_order value) and a query to retrieve the next row(s) using the information available in the previous iteration.The documentation and/or online resources can walk you through the specifics.David J.
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