Re: Why the "UPDATE tab SET tab.col" is invalid? - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Why the "UPDATE tab SET tab.col" is invalid?
Date
Msg-id 1466.1460036567@sss.pgh.pa.us
Whole thread Raw
In response to Why the "UPDATE tab SET tab.col" is invalid?  ("postgres_sure"<postgres_sure@163.com>)
List pgsql-hackers
"postgres_sure"<postgres_sure@163.com> writes:
> I found "Do not include the table's name in the specification of a target column
>                  — for example, UPDATE tab SET tab.col = 1 is invalid." in the documentation. 

> Some people usually like to update table by alias. They want to add this feature.

Sorry, but we aren't ever going to accept such a patch, because it would
introduce an unavoidable ambiguity: is "SET a.b = " meant to be an
assignment to column b of table a, or is it meant to be an assignment to
sub-field b of composite column a?

Yeah, we could invent some resolution rules to deal with that, but
better to just not add the nonstandard syntax (and it IS nonstandard,
SQL:2011 has nothing about it) in the first place.
        regards, tom lane



pgsql-hackers by date:

Previous
From: Geoff Winkless
Date:
Subject: Re: Why the "UPDATE tab SET tab.col" is invalid?
Next
From: Peter Geoghegan
Date:
Subject: Re: Using quicksort for every external sort run