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From: Thomas Kellerer <[email protected]>
To: [email protected]
Subject: Re: How to remove duplicates in an array and maintain the order?
Date: Sat, 8 Jul 2023 18:19:10 +0200
Message-ID: <[email protected]> (raw)
In-Reply-To: <CA+i5JwbwFsa2nHM+MG4mXinxx_fEzQGPrpUcz=T8yGDWPQrmnw@mail.gmail.com>
References: <CA+i5JwbwFsa2nHM+MG4mXinxx_fEzQGPrpUcz=T8yGDWPQrmnw@mail.gmail.com>



Shaozhong SHI schrieb am 08.07.2023 um 17:30:
> How to remove duplicated values in an array and maintain the order?

You can use distinct on ()

select array_agg(val order by idx)
from (
   select distinct on (val) val, idx
   from unnest(array[7,7,5,6,2,2,3,8,7,5,4,1,5]) with ordinality as t(val,idx)
   order by val, idx
) x


This picks the first occurrance of each element.
If you want to get the last occurrance of each value use "order by val, idx desc" in the inner select

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