How can I extract the values from a record as individual columns in postgresql

Question

How can I extract the values from a record as individual comuns in postgresql

SELECT 
p.*,
(SELECT ROW(id,server_id,format,product_id) FROM products_images pi WHERE pi.product_id = p.id LIMIT 1) AS image

FROM products p

WHERE p.company = 1 ORDER BY id ASC LIMIT 10

Instead of

image 
(3, 4, "jpeg", 7)

I would like to have

id | server_id | format | product_id
3  | 4         | jpeg   | 7

Is there any way of selecting only one image for each product and return the columns directly instead of a record?

Answer 1

Try this:

create type xxx as (t varchar, y varchar, z int);

with a as
(
select row(table_name, column_name, (random() * 100)::int) x 
from information_schema.columns
)
-- cannot cast directly to xxx, should cast to text first
select (x::text::xxx).t, (x::text::xxx).y, (x::text::xxx).z
from a

Alternatively, you can do this:

with a as
(
select row(table_name, column_name, (random() * 100)::int) x 
from information_schema.columns
), 
-- cannot cast directly to xxx, should cast to text first
b as (select x::text::xxx as w from a)

select 
(w).t, (w).y, (w).z
from b

To select all fields:

with a as
(
select row(table_name, column_name, (random() * 100)::int) x 
from information_schema.columns
), 
-- cannot cast directly to xxx, should cast to text first
b as (select x::text::xxx as w from a)

select
(w).*
from b

You can do this too, but this makes the whole exercise of using ROW a pointless one when you can just remove the ROW function and re-pick it up from outside of cte/derived table. I surmised the OP's ROW came from a function; for which he should use the codes above, not the following:

with a as
(
select row(table_name, column_name, (random() * 100)::int)::xxx x 
from information_schema.columns
)
select 
(x).t, (x).y, (x).z
from a