How to unpivot a table in PostgreSQL

Question

I am having difficulties writing a Postgres function, as I am not familiar with it. I have multiple tables to import into Postgres with this format:

id | 196         


        

Answer 1

The simplest way is a union all:

select id, 1960 as year, "1960" as value
from table t
union all
select id, '1960', "1961"
from table t
. . .;

A somewhat more sophisticated way would be:

select t.id, s.yr,
       (case when s.yr = 1960 then "1960"
             when s.yr = 1961 then "1961"
             . . .
        end) as value
from table t cross join
     generate_series(1960, 1980) s(yr);

You can put this into another table using insert or create table as.