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Re: column update order

From: Robert Klemme <shortcutter_at_googlemail.com>
Date: Tue, 21 Nov 2006 17:48:42 +0100
Message-ID: <4sgov8Fvlo8fU1@mid.individual.net>


On 21.11.2006 15:31, Charles Hooper wrote:
> Note: Transaction Isolation Levels can be altered at the session level.
> The default transaction isolation level does not enforce that SELECTs,
> UPDATEs, INSERTs, and DELETEs will be consistent as of the start of the
> transaction. If a column value is updated and committed in another
> session, the changed values will be visible in the second session. For
> example:

 From all that I can tell this thread is not about multi session consistency but about column values referenced in an UPDATE statement. The original question was

<quote>
Is the following safe, can we rely on the order of the columns being updated? (Oracle 10g)

update t set old_date = current_date, current_date = sysdate; </quote>

I guess what the OP really wanted to know was whether it is safe to refer to a column value in an UPDATE statement in a right hand side expression and always get the /old/ value - even if the same column is referred to in a left hand side expression. And for all I know it is.

Kind regards

        robert Received on Tue Nov 21 2006 - 10:48:42 CST

Original text of this message

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