July 2, 2013 at 1:34 pm
I have a table for instructors which contains subjects, date and time and Status information about their classes.
Once they register on the website they get the pending status, and somebody from administration either Approve, deny or Cancel their class.
so the status changes from Pending to either Approv, deny Or cancel.
I want to write a query that to piush the information to instructors if their Status gets changed from Pending to Approve, Deny Or Cancel
How do I do that.
Thaks,
Blyzzard
July 2, 2013 at 3:01 pm
Without having some way of knowing the previous status there is no query that can accomplish this.
If you add a trigger or modify the update logic to write either a flag or an audit record you could accomplish it.
But what you have described would typically be stored in a single field of a single row. So we only know the current state. How or if it changed cannot be determined..
CEWII
July 2, 2013 at 6:50 pm
Eliot's answer is basically correct but you could use the OUTPUT statement instead of a trigger.
Something like:
CREATE TABLE #StatusChanges (Status1 VARCHAR(20), Status2 VARCHAR(20));
UPDATE YourTable
SET Status = 'Approved'
OUTPUT DELETED.Status, INSERTED.Status
INTO #StatusChanges
WHERE ;-- whatever your WHERE criteria should be to avoid updates to all rows
SELECT *
FROM #StatusChanges
WHERE Status1 = 'Active' AND Status2='Approved'; -- Or whatever status changes you're looking for
My thought question: Have you ever been told that your query runs too fast?
My advice:
INDEXing a poor-performing query is like putting sugar on cat food. Yeah, it probably tastes better but are you sure you want to eat it?
The path of least resistance can be a slippery slope. Take care that fixing your fixes of fixes doesn't snowball and end up costing you more than fixing the root cause would have in the first place.
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July 5, 2013 at 12:21 pm
Will it be possible to capture instructor's email in the new temp table along with deleted status and inserted status so we know which instructor has got the new status?
Thanks,
Blyzzard
July 5, 2013 at 12:55 pm
I hate doing this in individual emails, since I think it's a poor design practice. Over time, or when things are busy, people get tons of emails that aren't necessary. This isn't really real-time information.
I'd use OUTPUT or a trigger and insert the values into a logging table. Then I'd send emails every 10, 20, 30 minutes, reading the logging table, looking for changes and emailing people with the changes.
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