Re: [PATCHES] extension for sql update

Tom Lane wrote:
> much anything that can generate a row.  The patch as you have it
> provides nothing more than syntactic sugar for something people can do
> anyway.  The reason people want this syntax is that they expect to be
> able to write, say,
>
>     UPDATE mytab SET (foo, bar, baz) =
>         (SELECT alpha, beta, gamma FROM othertab WHERE key = mytab.key);
>
> and with something like that you can't break apart the row-valued
> expression in the grammar.  So in reality the feature has to propagate
> much further into the backend than this.

That UPDATE example is interesting because I remember when using
Informix that I had to do a separate SELECT statement for each UPDATE
column I wanted to update.  I didn't realize that you could group
columns and assign them from a single select --- clearly that is a
powerful syntax we should support some day.

--
  Bruce Momjian   bruce@momjian.us
  EnterpriseDB    http://www.enterprisedb.com

  + If your life is a hard drive, Christ can be your backup. +