Pivoting a column based on sort order but with same name in PostgreSQL

Question

I have a CTE where i'm getting the details as below.I want this result to be pivoted based on the position.But the column name need to be same(if not can be different).

Sample output is given below,Can anyone suggest or help on this?

PostgreSQL version 11

Table have nearly 2000 ID's and up-to 10 links. Sample input:

   ID              LINK                                Position
    757 "https://www.shop.com/product/5/_/5_142_40.jpg" 4
    757 "https://www.shop.com/product/3/_/3_347_44.jpg" 2
    757 "https://www.shop.com/product/4/_/4_207_43.jpg" 3
    757 "https://www.shop.com/product/2/_/2_416_44.jpg" 1
    758 "https://www.shop.com/product/5/_/5_142_39.jpg" 4
    758 "https://www.shop.com/product/4/_/4_207_42.jpg" 3
    758 "https://www.shop.com/product/3/_/3_347_43.jpg" 2
    758 "https://www.shop.com/product/2/_/2_416_43.jpg" 1
    760 "https://www.shop.com/product/5/_/5_142_42.jpg" 4

Sample output:

ID   link                      link                link                link
757 .../2/_/2_416_44.jpg   ../3/_/3_347_44.jpg  ../4/_/4_207_43.jpg  ../5/_/5_142_40.jpg
758 .../2/_/2_416_43.jpg   ../3/_/3_347_43.jpg  ../4/_/4_207_42.jpg. ../5/_/5_142_39.jpg
760 ../5/_/5_142_42.jpg

Answer 1

You can use row_number() and conditional aggregation. The column names need to be different though:

with mycte as (...) -- your cte here
select
    id,
    max(link) filter(where rn = 1) link1,
    max(link) filter(where rn = 2) link2,
    max(link) filter(where rn = 3) link3,
    max(link) filter(where rn = 4) link4
from (
    select c.*, row_number() over(partition by id order by position) rn
    from mycte c
) t
group by id