On Thu, May 08, 2008 at 08:44:46AM +0200, Martijn van Oosterhout wrote:
> On Wed, May 07, 2008 at 03:04:49PM -0700, David Fetter wrote:
> > 1. Create a generic (possibly overloaded) trigger function,
> > bundled with PostgreSQL, which sets a field to some value. For
> > example, a timestamptz version might set the field to now().
>
> Doesn't the SQL standard GENERATED BY functionality work for this?
> Or won't that handle updates?
It appears to, at least according to 6WD2_02_Foundation_2007-12.pdf :)
4.14.8 Base columns and generated columns
A column of a base table is either a base column or a generated column. A base column is one that is not a
generatedcolumn. A generated column is one whose values are determined by evaluation of a generation expression, a
<valueexpression> whose declared type is by implication that of the column. A generation expression can reference
basecolumns of the base table to which it belongs but cannot otherwise access SQL data. Thus, the value of the field
corresponding to a generated column in row R is determined by the values of zero or more other fields of R. A
generatedcolumn GC depends on each column that is referenced by a <column reference> in its generation expression,
andeach such referenced column is a parametric column of GC.
Cheers,
David.
--
David Fetter <david@fetter.org> http://fetter.org/
Phone: +1 415 235 3778 AIM: dfetter666 Yahoo!: dfetter
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