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Re: SQL design pattern for a delta trigger?

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Vivek Khera wrote:
On Dec 7, 2007, at 11:42 AM, Colin Wetherbee wrote:

You can do this with a conditional. Something like the following should work.

IF
 NOT (a query matching your data returns rows)
THEN
 INSERT (your new data)

There exists a race condition here unless you've locked your tables.

Yes, clearly. In the context of the thread, I was assuming my algorithm would be implemented as an atomic transaction.

For what it's worth, the real algorithm would be as follows. I hadn't had enough coffee yet, and I forgot the UPDATE bit.

IF
  (a query matching your old data returns rows)
THEN
  UPDATE with your new data
ELSE
  INSERT your new data

Colin

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