From: Achilleas Mantzios <achill@matrix.gatewaynet.com>
Organization: Dynacom Tankers Mgmt
To: pgsql-sql@postgresql.org
Subject: Re: can someone explain confusing array indexing nomenclature
Date: Fri, 16 Feb 2007 10:34:42 +0200
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=CE=A3=CF=84=CE=B9=CF=82 =CE=A0=CE=AD=CE=BC=CF=80=CF=84=CE=B7 15 =CE=A6=CE=
=B5=CE=B2=CF=81=CE=BF=CF=85=CE=AC=CF=81=CE=B9=CE=BF=CF=82 2007 18:55, =CE=
=BF/=CE=B7 chrisj =CE=AD=CE=B3=CF=81=CE=B1=CF=88=CE=B5:
> Thanks Achilleas,
>
> I see what you are saying, but if we consider just the index "[2]" for a
> moment,
> it means something different depending upon the context  (in one case it
> means "2" and in the other case it means "1:2") and the context is
> determined by the format of indexes on other dimensions.
>
> I believe I understand....but incredibly confusing.
>

Now that i think about it again, i speculate that the [2] is discarded.

> - chris
>
> Achilleas Mantzios wrote:
> > =CE=9E=C2=A3=CE=9F=C2=84=CE=9E=CE=89=CE=9F=C2=82 =CE=9E=EF=BF=BD=CE=9E=
=CE=85=CE=9F=C2=84=CE=9E=C2=AC=CE=9F=C2=81=CE=9F=C2=84=CE=9E=C2=B7 14 =CE=
=9E=C2=A6=CE=9E=CE=85=CE=9E=C2=B2=CE=9F=C2=81=CE=9E=CE=8F=CE=9F=C2=85=CE=9E=
=C2=AC=CE=9F=C2=81=CE=9E=CE=89=CE=9E=CE=8F=CE=9F=C2=82 2007 21:31, =CE=9E=
=CE=8F/=CE=9E=C2=B7 chrisj=20
=CE=9E=C2=AD=CE=9E=C2=B3=CE=9F=C2=81=CE=9E=C2=B1=CE=9F=C2=88=CE=9E=CE=85:
> >> given the following table:
> >>
> >> protocal2=3D> select * from sal_emp ;
> >>  name  |      pay_by_quarter       |                 schedule
> >> -------+---------------------------+----------------------------------=
=2D-
> >>--- ---- Bill  | {10000,10000,10000,10000} |
> >> {{meeting,lunch},{training,presentation}}
> >>  Carol | {20000,25000,25000,25000} |
> >> {{breakfast,consulting},{meeting,lunch}}
> >> (2 rows)
> >>
> >> why do the following two queries yield different results??
> >>
> >> protocal2=3D> SELECT schedule[1][2] FROM sal_emp WHERE name =3D 'Bill';
> >>  schedule
> >> ----------
> >>  lunch
> >> (1 row)
> >>
> >> protocal2=3D> SELECT schedule[1:1][2] FROM sal_emp WHERE name =3D 'Bil=
l';
> >>      schedule
> >> -------------------
> >>  {{meeting,lunch}}
> >> (1 row)
> >
> > The [n:m] notation denotes a slice of the array (not element).
> > So schedule[1][2] is the Array element on 2nd col of 1st row,
> > while schedule[1:1][2] could mean
> > the second row of the subarray schedule[1:1][1:2].
> > So these two are foundamentally different things.
> > In my 7.4 even if you gave
> > SELECT schedule[1:1][888] FROM sal_emp WHERE name =3D 'Bill';
> > you would still get  {{meeting,lunch}} as a result.
> > (Right or wrong is another story).
> > Anyway the first time you query for a "text",
> > the second time you query for a "text[]", so you should expect
> > different results.
> > --
> > Achilleas Mantzios
> >
> > ---------------------------(end of broadcast)---------------------------
> > TIP 3: Have you checked our extensive FAQ?
> >
> >                http://www.postgresql.org/docs/faq

=2D-=20
Achilleas Mantzios