Re: Group By aggregate string function

Hi Lance

first of all you should check your data-model.
If there are different roles or jobs in a certain order, you should
better bring these jobs in theier own table.
So it is easy to have them ordered.

But you can do some tricks to treat them as array elements
Not nice but it works

create table staff(id integer, user text, job text);
insert some data ...

select id, usr, ar[pos] from (select id, usr,
min(array_position(array['admin', 'manager'], job)) as pos,
array['admin', 'manager'] as ar from staff where usr='lance' group by
id, usr, ar)
as test;
 id |  usr  |  ar
----+-------+-------
  1 | lance | admin

Regards Martin

Am 21.02.2019 um 20:02 schrieb Campbell, Lance:
>
> Correction. I had two typos.  I did not want to confuse someone.
>
> PostgreSQL 10.x
>
> Below is my situation.  I need some kind of aggregate string function
> that when it finds multiple string values it will order them based on
> a preferred preference.  Example: “admin”, then “manager” then “…”.
>
> Table T
>
> fk_id int – foreign key
>
> user_id  text
>
> role text  - possible values could be “admin” and “manager”
>
> Primary key (fk_id, user_id, role)
>
> Sample data:
>
> 1. lance  admin
>
> 1     lance manager
>
> 87   bob   manager
>
> 98   tom admin
>
> 104 tom manager
>
> SELECT fk_id, user_id, some-aggregate-string-function(role, “admin”,
> “manager”)  FROM T  WHERE user_id = ‘lance’ GROUP BY fk_id, user_id;
>
> When selecting data if there are multiple rows within the group by
> then aggregate the result based on a priority for role of “admin”
> first, “manager” second, etc.
>
> Expected Result:
>
> 1 lance admin
>
> Ignores the second record with lance in it because the first record
> contained admin.
>
> THANKS!
>
> *From: *Lance Campbell <lance(at)illinois(dot)edu>
> *Date: *Thursday, February 21, 2019 at 1:00 PM
> *To: *"pgsql-sql(at)postgresql(dot)org" <pgsql-sql(at)postgresql(dot)org>
> *Subject: *Group By aggregate string function
>
> PostgreSQL 10.x
>
> Below is my situation.  I need some time of aggregate string function
> that when it finds multiple string values it will order them based on
> a preferred preference.  Example:  “admin”, then “manager” then “…”.
>
> Table T
>
> fk_id int – foreign key
>
> user_id  text
>
> role text  - possible values could be “admin” and “manager”
>
> Primary key (fk_id, user_id, role)
>
> Sample data:
>
> 1. lance  admin
>
> 1     lance manager
>
> 87   bob   manager
>
> 98   tom admin
>
> 104 tom manager
>
> SELECT fk_id, user_id, some-aggregate-string-function(role, “admin”,
> “manager”)  FROM T  WHERE user_id = ‘lance’ GROUP BY fk_id, user_id;
>
> When selecting data if there are multiple rows within the group by
> then aggregate the result based on a priority for role of “admin”
> first, “manager” second, etc.
>
> Expected Result:
>
> 1 lance admin
>
> Ignores the second record with lance in it because it contains admin.
>
> THANKS!
>
> *LANCE CAMPBELL <https://directory.illinois.edu/person/lance>*
>
> /Software Architect/
>
> Web Services <https://webtools.illinois.edu/>
>
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>
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>
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>
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