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Replacing IDENTITY with lastval()

From: Dmitry Samokhin <sdld(at)mail(dot)ru>
To: pgsql-odbc(at)postgresql(dot)org
Subject: Replacing IDENTITY with lastval()
Date: 2007-05-04 11:42:37
Message-ID: E1HjwBJ-000Hnc-00.sdld-mail-ru@f105.mail.ru (view raw or flat)
Thread:
Lists: pgsql-odbc
Accordind to the release notes, "Use lastval() function to replace IDENTITY on 8.1 or later servers" was introduced in release 8.2.0205. This may cause incorrect results: "<...> assumes that your database does not expect any triggers to fire when the INSERT is executed. If a trigger does fire and if that trigger adds another row to a table, the @@IDENTITY global variable would be set to point to that new Identity value—not the one your INSERT generated. <...> work for simple situations, but not when your database gets more sophisticated".
See "Managing an @@IDENTITY Crisis" on MSDN (http://msdn2.microsoft.com/en-us/library/ms971502.aspx) for more details.

The PostgreSQL documentation states that the lastval() function returns the value most recently returned by nextval in the current session. It works the same way as the @@IDENTITY variable in MSSQL. The currval(...) function returns a value of the explicitly specified sequence, this is exactly what we need.

Please consider to revert the code.

Regards,
Dmitry.

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