| From: | hubert depesz lubaczewski <depesz(at)depesz(dot)com> |
|---|---|
| To: | "Ila B(dot)" <ilaria(dot)battiston(at)gmail(dot)com> |
| Cc: | pgsql-sql(at)lists(dot)postgresql(dot)org |
| Subject: | Re: Top 3 values for each group in PGSQL |
| Date: | 2019-03-01 11:59:11 |
| Message-ID: | 20190301115911.7hbvcw3pkhwz5wg5@depesz.com |
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| Thread: | |
| Lists: | pgsql-sql |
On Fri, Mar 01, 2019 at 11:51:24AM +0100, Ila B. wrote:
> Hello,
>
> I’m working on a health database and I’m trying to extract the most popular prescription codes from a custom table I structured like this:
>
> Year - Code - Count(code)
>
> I want to extract the 3 codes with maximum count for each year. I know I should be using rank() but I don’t really understand how this works.
> I am using pgAdmin4 version 3.5 with PostgreSQL 10.6 on Windows 10 Pro and no permission to update.
Consider reading
https://www.depesz.com/2012/10/05/getting-top-n-rows-per-group/
Best regards,
depesz
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