How to count rows based on a column value

Question

I am using Posgresql and I want to write a query to perform the following. Suppose the table is like this:

id section views
1 1 10
2 2 8
3 1 20
4 1 21
5 2 0

I want to count each row that has the same "section" value (ordered by "views") like this:

 id section views contador 
 4 1 21 1 //section 1 contador 1
 3 1 20 2 //section 1 contador 2 ...
 1 1 10 3
 2 2 8 1 //section 2 contador 1
 5 2 0 2 //section 2 contador 2

Answer 1

You need to use a Window Function like row_number()

SELECT
 id,
 section,
 views,
 row_number() OVER (PARTITION BY section ORDER BY views DESC)
FROM table;