ottenm
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trigger help with columns_updated
In SQL 2000, is it possible to create a trigger that only fires when the data in a particular column has been changed? I can't find an explanation or and example of columns_updated that would answer this for me. What is the syntax for columns_updated? And does it "report" all the columns in the "UPDATE" statement? Or just the ones where the new data being assigned is actually different from what was there?
My hope is to create a trigger for the table order_entry, that will set the field 'exported' to null, whenever the value in the field 'freight_amount' actually changes.
Thanks for any help.
My hope is to create a trigger for the table order_entry, that will set the field 'exported' to null, whenever the value in the field 'freight_amount' actually changes.
Thanks for any help.
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dportas: proc sounds good enough, thanks for the suggestion.
chapmandew: wrong article? (link is on "dates tables")
thanks to both-
chapmandew: wrong article? (link is on "dates tables")
thanks to both-
It's much clearer and easier to use "UPDATE(column_name)", for example:
CREATE TRIGGER order_entry_trig_set_expor
ON order_entry
AFTER UPDATE
AS
IF @@ROWCOUNT = 0
RETURN
IF UPDATE(freight_amount)
BEGIN
UPDATE order_entry
SET exported = NULL
FROM order_entry
INNER JOIN inserted ON inserted.keyCol = order_entry.keyCol --AND ~.keyCol2 = ~~.keyCol2 ...
INNER JOIN deleted ON deleted.keyCol = order_entry.keyCol --AND ~.keyCol2 = ~~.keyCol2 ...
WHERE (inserted.freight_amount <> deleted.freight_amount)
OR (inserted.freight_amount IS NULL AND deleted.freight_amount IS NOT NULL)
OR (inserted.freight_amount IS NOT NULL AND deleted.freight_amount IS NULL)
END --IF
GO
CREATE TRIGGER order_entry_trig_set_expor
ON order_entry
AFTER UPDATE
AS
IF @@ROWCOUNT = 0
RETURN
IF UPDATE(freight_amount)
BEGIN
UPDATE order_entry
SET exported = NULL
FROM order_entry
INNER JOIN inserted ON inserted.keyCol = order_entry.keyCol --AND ~.keyCol2 = ~~.keyCol2 ...
INNER JOIN deleted ON deleted.keyCol = order_entry.keyCol --AND ~.keyCol2 = ~~.keyCol2 ...
WHERE (inserted.freight_amount <> deleted.freight_amount)
OR (inserted.freight_amount IS NULL AND deleted.freight_amount IS NOT NULL)
OR (inserted.freight_amount IS NOT NULL AND deleted.freight_amount IS NULL)
END --IF
GO
Sorry about that...I had posted that on another question, and I guess it was still on my clipboard. At any rate, have a look at this article....it will give you an idea on how columns_updated() works.
http://www.zdnetasia.com/techguide/database-management/0,3800010795,62042223,00.htm
http://www.zdnetasia.com/techguide/database-management/0,3800010795,62042223,00.htm
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