Postgres Update with json to record? - json

Question

i try to find a simple solution to update data with the json_to_record statement. I want to update the data every night with a json_array i get by web_craping. Any idea how i can solve the problem when theres a new article?
Thanks a lot :)
INSERT INTO prices
Select * from
json_to_record(
'{"distributor“: "1", "articelnr": 4711, "price": „700“, "delivery": "too late", "created_on": "2022-09-25 03:14:07"}'
) AS x(distributor INT, articelnr VARCHAR, price VARCHAR, delivery VARCHAR, created_on TIMESTAMP)
Is it possible to use an update statement in a similar way like:
UPDATE prices
SET
json_to_record(
'{"distributor“: "1", "articelnr": 4711, "price": „700“, "delivery": "too late", "created_on": "2022-09-25 03:14:07"}'
) AS x(distributor INT, articelnr VARCHAR, price VARCHAR, delivery VARCHAR, created_on TIMESTAMP)

Answer 1

According to UPDATE syntax it is possible to update a table using a sub-select, e.g.:
update prices set
(distributor, articelnr, price, delivery, created_on) =
(
select *
from json_to_record(
'{"distributor": "1", "articelnr": 4711, "price": "700", "delivery": "too late", "created_on": "2022-09-25 03:14:07"}'
) as x(distributor int, articelnr varchar, price varchar, delivery varchar, created_on timestamp)
)
where distributor = 1 and articelnr = 4711
Unfortunately, the sub-select results are not visible in the WHERE clause. Hence using the query in the FROM section seems more suitable, e.g.:
update prices p set
(distributor, articelnr, price, delivery, created_on) =
(x.distributor, x.articelnr, x.price, x.delivery, x.created_on)
from (
select *
from json_to_record(
'{"distributor": "1", "articelnr": 4711, "price": "700", "delivery": "too late", "created_on": "2022-09-25 03:14:07"}'
) as x(distributor int, articelnr varchar, price varchar, delivery varchar, created_on timestamp)
) as x
where p.distributor = x.distributor and p.articelnr = x.articelnr
Note, that you need unique columns (typically a primary key) to identify a row to update. Examples assume that they are (distributor, articelnr).