Обсуждение: pg 9.1beta3 typo in 7.2.3

I think that there is a typo in the paragraph: 'x' used instead of 'y'
in 'GROUP BY'.

postgres-9.1beta3/share/doc/html/queries-table-expressions.html


7.2.3. The GROUP BY and HAVING Clauses
[...]
=> SELECT x FROM test1 GROUP BY x;
  x
---
  a
  b
  c
(3 rows)

In the second query, we could not have written SELECT * FROM test1 GROUP
BY x, because there is no single value for the column y that could be
associated with each group. The grouped-by columns can be referenced in
the select list since they have a single value in each group.
[...]

The paragraph should read "...SELECT * FROM test1 GROUP BY y..."


Cheers,
Gavin

Gavin Flower <GavinFlower@archidevsys.co.nz> writes:
> I think that there is a typo in the paragraph: 'x' used instead of 'y'
> in 'GROUP BY'.

You're mistaken.  However, possibly the example is a bit confusing,
because the point is that "SELECT *" includes y, which can't be validly
referenced.  Maybe we should spell out "x, y" instead of writing "*".

            regards, tom lane