Re: Count column with name 'count' returns multiple rows. Why?

On 2017-08-18 15:57:39 -0500, Justin Pryzby wrote:
> On Fri, Aug 18, 2017 at 10:47:37PM +0200, Peter J. Holzer wrote:
> > On 2017-08-18 06:37:15 -0500, Justin Pryzby wrote:
> > > On Fri, Aug 18, 2017 at 01:01:45PM +0200, Rob Audenaerde wrote:
> > > > Can anyone please explain this behaviour?
> > >
> > > https://www.postgresql.org/docs/9.6/static/sql-expressions.html#SQL-EXPRESSIONS-FUNCTION-CALLS
> > > https://www.postgresql.org/docs/9.6/static/rowtypes.html#ROWTYPES-USAGE
> >
> > Maybe I overlooked it, but I don't see anything in those pages which
> > explains why «count» is parsed as a column name in the first example and
> > as a function name in the second.
> >
> > Nor do I see what «count(base.*)» is supposed to mean. It seems to be
> > completely equivalent to just writing «count», but the part in
> > parentheses is not ignored: It has to be either the table name or the
> > table name followed by «.*». Everything else I tried either led to a
> > syntax error or to «count» being recognized as a function. So apparently
> > columnname open-parenthesis tablename closed-parenthesis is a specific
> > syntactic construct, but I can't find it documented anywhere.
>
> | Another special syntactical behavior associated with composite values is that
> |we can use functional notation for extracting a field of a composite value. The
> |simple way to explain this is that the notations field(table) and table.field
> |are interchangeable. For example, these queries are equivalent:

Thanks. I see it now.

hp

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