[SQL] get attribute from XML

[Viktor Bojović]

Hi,
while parsing this type of XML:

Q91G55

i tried this query to get the modified attribute
select xpath('//entry/modified/text()',xml) from xml_sprot limit 10;
but it doesn't work.

So im asking if anyone can help me with that.

Thanx in advance
-- 
---
Viktor Bojović
---
Wherever I go, Murphy goes with me

Re: [SQL] get attribute from XML

[Markus Schatten]

Dear Viktor,

'modified' is an attribute node, so you need to use the @ sign to
acquire its value:

mschatte=# select xpath( '//entry/@modified', '' );
xpath
--
 {2009-07-07}
(1 row)

HTH

M.S.

On Tue, Oct 12, 2010 at 1:03 AM, Viktor Bojović
 wrote:
> Hi,
> while parsing this type of XML:
> 
> Q91G55
>
> i tried this query to get the modified attribute
> select xpath('//entry/modified/text()',xml) from xml_sprot limit 10;
> but it doesn't work.
> So im asking if anyone can help me with that.
> Thanx in advance
> --
> ---
> Viktor Bojović
> ---
> Wherever I go, Murphy goes with me
>

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[SQL] Is there a conditional string-concatenation ?

[Andreas]

 Hi,
Is there a conditional string-concatenation ?

I'd like to have an elegant way to connect 2 strings with some 3rd 
element between only if there really are 2 strings to connect.


e.g.
MyCat ( 'John', '_', 'Doe' ) --> 'John_Doe'
while
MyCat ( 'John', '_', '' ) --> 'John'
MyCat ( '', '_', 'Doe' ) --> 'Doe'
MyCat ( '', '_', '' ) --> NULL

It should treat  NULL  and  ''  equally as empty
and it should trim each of the 3 elements.

so
MyCat ( '   John ', '_', NULL ) --> 'John'
MyCat ( 'John', NULL, 'Doe' ) --> 'JohnDoe'



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Re: [SQL] Is there a conditional string-concatenation ?

[Joshua Tolley]

On Tue, Oct 12, 2010 at 06:09:07AM +0200, Andreas wrote:
>  Hi,
> Is there a conditional string-concatenation ?

Perhaps this:

CREATE OR REPLACE FUNCTION mycat(text, text, text) RETURNS TEXT LANGUAGE sql
IMMUTABLE AS $$
SELECT CASE
WHEN $1 IS NULL OR $1 = '' THEN trim($3)
WHEN $3 IS NULL OR $3 = '' THEN trim($1)
ELSE trim($1) || trim(coalesce($2, '')) || trim($3)
END;

--
Joshua Tolley / eggyknap
End Point Corporation
http://www.endpoint.com


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Re: [SQL] Is there a conditional string-concatenation ?

[Osvaldo Kussama]

2010/10/12 Andreas :
>  Hi,
> Is there a conditional string-concatenation ?
>
> I'd like to have an elegant way to connect 2 strings with some 3rd element
> between only if there really are 2 strings to connect.
>
> e.g.
> MyCat ( 'John', '_', 'Doe' ) --> 'John_Doe'
> while
> MyCat ( 'John', '_', '' ) --> 'John'
> MyCat ( '', '_', 'Doe' ) --> 'Doe'
> MyCat ( '', '_', '' ) --> NULL
>
> It should treat  NULL  and  ''  equally as empty
> and it should trim each of the 3 elements.
>
> so
> MyCat ( '       John     ', '_', NULL ) --> 'John'
> MyCat ( 'John', NULL, 'Doe' ) --> 'JohnDoe'
>


Try:
bdteste=# SELECT nullif(ltrim(rtrim(coalesce(c1,'') || coalesce(c2,'')
|| coalesce(c3,''),' _'),' _'),'')
bdteste-#   FROM (VALUES ('John', '_', 'Doe'),('John', '_', ''),('',
'_', 'Doe'),('', '_', ''),('   John ', '_', NULL),('John',
NULL, 'Doe')) AS foo(c1,c2,c3);
  nullif
--
 John_Doe
 John
 Doe

 John
 JohnDoe
(6 rows)

Osvaldo

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