PostgreSQL - finding and updating multiple records

Question

I have a table:

ID | rows | dimensions
---+------+----------- 
1  |  1   |   15 x 20
2  |  3   |   2  x 10
3  |  5   |   23 x 33
3  |  7   |   15 x 23 
4  |  2   |   12 x 32    

And I want to have something like that:

ID | rows | dimensions
---+------+----------- 
1  |  1   |   15 x 20
2  |  3   |   2  x 10
3a |  5   |   23 x 33
3b |  7   |   15 x 23 
4  |  2   |   12 x 32  

How can I find the multiple ID value to make it unique?

How can I update the parent table after?

Thanks for your help!

Answer 1

with stats as (
    SELECT "ID", 
           "rows",
           row_number() over (partition by "ID" order by rows) as rn,
           count(*) over (partition by "ID") as cnt
    FROM Table1
)
UPDATE Table1
   SET "ID" = CASE WHEN s.cnt > 1 THEN s."ID" || '-' || s.rn 
                   ELSE s."ID"
              END
  FROM stats s
 WHERE S."ID" = Table1."ID"
   AND S."rows" = Table1."rows"

I'm assuming you cant have two rows with same ID and same rows other wise you need to include "dimensions" on the WHERE too.

In this case the output is