Updating a field with the result of a select
Hi,
Is it possible to update a field with the result of a select. For example:
UPDATE ordr_order SET balance = ('SELECT ordr_order.total_cost -
sum(ordr_payment.amount) FROM ordr_order LEFT JOIN ordr_payment on
ordr_payment.ordr_order_id = ordr_order.id WHERE ordr_order.id = 1') WHERE
id = 1
When I execute this query, I don't get an error, but it also doesn't update
the field in question. If I execute each query separately, they each work
fine.
Thanks for your help.
Daniel Leighton
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RE: Updating a field with the result of a select
Is it possible to update a field with the result of a select.
For example:
Try:
SELECT @newbalance := ordr_order.total_cost - sum(ordr_payment.amount) FROM
ordr_order LEFT JOIN ordr_payment on ordr_payment.ordr_order_id =
ordr_order.id WHERE ordr_order.id = 1;
UPDATE ordr_order SET balance = @newbalance WHERE id = 1;
UPDATE ordr_order SET balance = ('SELECT ordr_order.total_cost -
sum(ordr_payment.amount) FROM ordr_order LEFT JOIN ordr_payment on
ordr_payment.ordr_order_id = ordr_order.id WHERE ordr_order.id = 1')
WHERE id = 1
This doesn't work because it's setting balance to the text of the query, not
the result of the query itself. Since balance is probably not a string type,
it gets converted to a number which probably ends up making it zero. If
MySQL supported subselects it might work except without the single quotes
around the query.
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