xml

2015-03-23 12:40 GMT+01:00 Ramesh T <rameshparnanditech@gmail.com>:

Hi all,
SELECT xmlagg(xmlelement(
name actor, xmlattributes(first_name)
)ORDER BY actor_id,',')from actor;

the above code return following result,

[image: Inline image 1]
Question :

i want retrieve result from above XML result like
penelope,nick,jennifer,jhony,,,,,

result of xmlagg is not valid xml.

if you use xmlelement, then you can get valid xml

ostgres=# select * from x;
a
---------------------------------------------------------------
<d><actor first_name="Pavel"/><actor first_name="Tomas"/></d>
(1 row)

postgres=# select unnest(xpath('//actor/@first_name',a)::text[]) from x;
unnest
--------
Pavel
Tomas
(2 rows)

Regards

Pavel

Pavel Stehule <pavel.stehule@gmail.com> writes:

result of xmlagg is not valid xml.

Really? Either that's a bug, or it's declared wrong.

regards, tom lane

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2015-03-23 15:09 GMT+01:00 Tom Lane <tgl@sss.pgh.pa.us>:

Pavel Stehule <pavel.stehule@gmail.com> writes:

result of xmlagg is not valid xml.

Really? Either that's a bug, or it's declared wrong.

I was not accurate. "<tag /><tag />" is not valid xml document - and xpath
function doens't like it.

postgres=# select xpath('//tag/@x','<tag x="x"/><tag />'::xml);
ERROR: could not parse XML document
DETAIL: line 1: Extra content at the end of the document
<tag x="x"/><tag />
^
CONTEXT: SQL function "xpath" statement 1
postgres=# select xpath('//tag/@x','<x><tag x="x"/><tag /></x>'::xml);
xpath
-------
{x}
(1 row)

postgres=# select '<tag x="x"/><tag />'::xml;
xml
---------------------
<tag x="x"/><tag />
(1 row)

Regards

Pavel