Обсуждение: arrays and polygons

Hi there i am having problems inserting an array of polygons into a table, i
have added the column using:

ALTER TABLE species ADD COLUMN location polygon[];

this works fine, but when i try

INSERT INTO species (location) VALUES ('{((432,89), (45,87), (89,87)),
((54,78), (34,98))};

I get the following error message:

ERROR: Bad polygon external representation '((432'

Where am i going wrong, all help is much appreciated DAvid

"David" <de4@kent.ac.uk> writes:
> ALTER TABLE species ADD COLUMN location polygon[];

> INSERT INTO species (location) VALUES ('{((432,89), (45,87), (89,87)),
> ((54,78), (34,98))};

I think you'd need to double-quote each polygon within the array
literal.
'{"((432,89), (45,87), (89,87))", "..."}'

The array parser doesn't think parens are special, so it's not going to
magically distinguish array commas from polygon commas for you.

BTW, if you are using 7.4, the ARRAY[] constructor syntax might be
easier to use.
        regards, tom lane

Thanks to you both that helped enormously, 

Dave


----- Original Message ----- 
From: "Joe Conway" <mail@joeconway.com>
To: "Tom Lane" <tgl@sss.pgh.pa.us>
Cc: "David" <de4@kent.ac.uk>; <pgsql-sql@postgresql.org>
Sent: Friday, February 13, 2004 4:33 PM
Subject: Re: [SQL] arrays and polygons


> Tom Lane wrote:
> > "David" <de4@kent.ac.uk> writes:
> >>INSERT INTO species (location) VALUES ('{((432,89), (45,87), (89,87)),
> >>((54,78), (34,98))};
> > 
> > I think you'd need to double-quote each polygon within the array
> > literal.
> > 
> > '{"((432,89), (45,87), (89,87))", "..."}'
> > 
> > The array parser doesn't think parens are special, so it's not going to
> > magically distinguish array commas from polygon commas for you.
> > 
> > BTW, if you are using 7.4, the ARRAY[] constructor syntax might be
> > easier to use.
> 
> FWIW, here's what it would look like in 7.4.x:
> 
> regression=# select ARRAY['((432,89), (45,87), (89,87))'::polygon, 
> '((432,89), (45,87), (89,87))'];
>                              array
> -------------------------------------------------------------
>   {"((432,89),(45,87),(89,87))","((432,89),(45,87),(89,87))"}
> (1 row)
> 
> You need to explicitly cast at least the first polygon in order to get 
> an array of polygons (versus an array of text).
> 
> HTH,
> 
> Joe
> 

Tom Lane wrote:
> "David" <de4@kent.ac.uk> writes:
>>INSERT INTO species (location) VALUES ('{((432,89), (45,87), (89,87)),
>>((54,78), (34,98))};
> 
> I think you'd need to double-quote each polygon within the array
> literal.
> 
>     '{"((432,89), (45,87), (89,87))", "..."}'
> 
> The array parser doesn't think parens are special, so it's not going to
> magically distinguish array commas from polygon commas for you.
> 
> BTW, if you are using 7.4, the ARRAY[] constructor syntax might be
> easier to use.

FWIW, here's what it would look like in 7.4.x:

regression=# select ARRAY['((432,89), (45,87), (89,87))'::polygon, 
'((432,89), (45,87), (89,87))'];                            array
-------------------------------------------------------------
{"((432,89),(45,87),(89,87))","((432,89),(45,87),(89,87))"}
(1 row)

You need to explicitly cast at least the first polygon in order to get 
an array of polygons (versus an array of text).

HTH,

Joe