I wonder if this works:
update stock s set s_superceded = true
where s.s_updated < (select max(t.s_updated) from stock t where t.s_vin = s.s_vin)
On Thu, May 14, 2009 at 7:27 AM, Gary Stainburn
<gary.stainburn@ringways.co.uk> wrote:
I know I should be able to do this but my brain's mashed today
I have a stock table with
s_stock_no varchar primary key
s_vin varchar
s_updated timestamp
s_superceded boolean
It is possible for the same vin to exist on stock if we have sold and then
bought back a vehicle, e.g. as a part exchange.
Every time a vehicle is inserted/updated the s_updated field is update.
How can I update the table so that for each s_vin, if a record does not have
the most recent s_updated value, s_superceded is set to true?
I can get the most recent value by running:
select * from (select s_vin,
count(s_updated) as numb,
max(s_updated)::timestamp as latest
from stock
group by s_vin) foo
where numb > 1;
but I can't seem to get how I can convert this to an update statement. The num
> 1 simply removed all vehicles with only one record.
I seem to think I need an update..... from..... statement
--
Gary Stainburn
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