Re: BUG #19003: A SELECT that does not return a valid table - Mailing list pgsql-bugs

PG Bug reporting form <noreply@postgresql.org> writes:

SELECT 'John' AS nom,'James' AS nom
returns a table with attributes nom and nom that I can see in the output.
Returning a table that contains twice the same column should not be
permitted.

There is pretty much zero chance that we will enforce that
restriction.  It would break too much application code.
Also, it looks to me like there is no such requirement in
the SQL standard.

Indeed.  In SQL:2023-1 (available free of charge at [1]) says in Subclause 4.6, "Tables":

    "An operation that references zero or more base tables and returns a table is called a *query*. The result of a query is called a *derived table*."

and

    "Derived tables, other than viewed tables, may contain more than one column with the same name."

So, not only is this not a bug we should fix, it is explicitly allowed by the standard.

[1] https://www.iso.org/standard/76583.html

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Vik Fearing
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