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

How can I extrac开发者_StackOverflowt 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?

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

Just specify the components of your struct:

SELECT a,b,c,(image).id, (image).server_id, ...
FROM (

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
) as subquery

But anyway, I would rework the query and use a join instead of a subclause.

 SELECT DISTINCT ON (p.*) p.*,
        p.id,pi.server_id,pi.format,pi.product_id
   FROM products p
   LEFT JOIN product_images pi ON pi.product_id = p.id
  WHERE p.company = 1 
  ORDER BY id ASC 
  LIMIT 10

But I believe you have to specify all the p-fields in the distinct separately to ensure just one image is loaded per product.

Try this, will work on your existing code with minimal modification(if creating a type is a minimal modification for you ;-)

create type image_type as (id int, server_id int, format varchar, product_id int);

SELECT 
p.*,
( (SELECT ROW(id,server_id,format,product_id) 
   FROM products_images pi 
   WHERE pi.product_id = p.id LIMIT 1)::text::image_type ).*

FROM products p

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

Proof-of-concept code:

Create type first:

create type your_type_here as (table_name varchar, column_name varchar)

Actual code:

select 
a.b, 
( (select row(table_name, column_name) 
   from information_schema.columns limit 1)::text::your_type_here ).*
from generate_series(1,10) as a(b)

But I guess you should tackle it with GROUP BY' andMAXcombo or useDISTINCT ON` like what Daniel have posted

every table has an associated composite type of the same name

https://www.postgresql.org/docs/current/plpgsql-declarations.html#PLPGSQL-DECLARATION-ROWTYPES

So, this code

drop table if exists "#typedef_image"
;
create temp table "#typedef_image"(
    id int,
    server_id int,
    format text,
    product_id int
    )
;
select (row(3, 4, 'jpeg', 7)::"#typedef_image").*

will work