Thread: updating records in table A from selected records in table B
I've pored over the syntax for UPDATE but I think I'm missing something.
Assuming a schema such as:
Column | Type |
Modifiers
--------------------+-----------------------------+------------------------------------------------------------
id | integer | not null default
nextval('service_bills_id_seq'::regclass)
fk | integer |
start_time | timestamp without time zone |
quantity | numeric(10,5) |
cost | numeric(10,5) |
Starting with the results from this query:
SELECT candidates.quantity, candidates.cost
FROM table_b AS candidates
INNER JOIN table_a AS incumbents
ON incumbents.fk = candidates.fk
AND incumbents.start_time = candidates.start_time
... is there a way to update quantity and cost fields in incumbents
with the matching records from candidates? It seems that UPDATE is
designed only to update one record at a time...
> ... is there a way to update quantity and cost fields in incumbents > with the matching records from candidates? It seems that UPDATE is > designed only to update one record at a time... Oh, no, it is certainly possible to do what you want here. The usual trick is: UPDATE sometable set somefield=somevalue where id in (select id from somecomplicatedsubquery) Maximilian Tyrtania Software-Entwicklung Dessauer Str. 6-7 10969 Berlin http://www.contactking.de
@Maximilian:
On Tue, Mar 29, 2011 at 22:46, Maximilian Tyrtania <lists@contactking.de> wrote:
>> It seems that UPDATE is designed only to update one record at a time...
>
> Oh, no, it is certainly possible to do what you want here. The usual trick is:
>
> UPDATE sometable set somefield=somevalue where id in (select id from somecomplicatedsubquery)
I may be misreading your reply, but I get
PGError: ERROR: missing FROM-clause entry for table "candidate"
With the following query:
UPDATE table_as SET incumbent.value = candidate.value
WHERE id IN ( SELECT id
FROM table_b AS candidates
INNER JOIN table_as AS incumbents
ON incumbents.key = candidate.key)
Is that what you meant?