i!
On Aug 14, 2006, at 7:14 PM, <mysql@stripped> <mysql@stripped>
wrote:
> I've looked on the internet, but the best thing I found is MyXML,
> which
> is simply too limited (and looks not supported). Is anyone currently
MyXML is a pretty trivial thing, and while I know of a few places
that use it, it does not have mass appeal :)
It is supported as far as bugs go, but no one has send me a bug on it
in years.
Cheers,
-Brian
> already working on this or is MySQL AB itself working on XML output
> functions.
>
> I've also got a direct question. What is exactly the function of
> group_concat_max_len? I got the impression that memory the size of
> group_concat_max_len is allocated for each group_concat call.
> If so, I hope to prevent doing the same using xmlwriter. I'm not sure,
> but at the first glance it looks like xmlwriter allocates memory
> dynamically.
>
> I'm not sure about performance; using lots of group_concat's can
> really
> slow a query down. But we'll just have to see after I've written some
> code.
>
> If anyone has any tips, remarks, etc, please let me know.
>
>
> ------
>
> Proposed syntax:
> SELECT xmlelement("root", xmlgroup(trunk.xmlnode)) FROM
> (SELECT xmlelement("trunk", xmlgroup(leaf.xmlnode),
> xmlattributes("id", trunk.id, "description", trunk.description)) AS
> xmlnode FROM tree_trunk LEFT JOIN
> (SELECT tree_trunk_id, xmlelement("leaf", NULL, xmlattributes
> ("id",
> tree_leaf.id, "description", tree_leaf.description)) AS xmlnode FROM
> tree_leaf) AS leaf ON tree_trunk.id = leaf.trunk_id
> GROUP BY tree_trunk.id) AS trunk
>
> ------
>
> Simulation:
> SELECT CONCAT_WS('', "<root>", GROUP_CONCAT(trunk.xmlnode SEPARATOR
> ''),
> "</root>") FROM
> (SELECT CONCAT_WS('', "<trunk id=", QUOTE(tree_trunk.id), "
> description=", QUOTE(tree_trunk.description), ">",
> GROUP_CONCAT(leaf.xmlnode SEPARATOR ''), "</trunk>") AS xmlnode FROM
> tree_trunk LEFT JOIN
> (SELECT tree_leaf.trunk_id, CONCAT_WS('', "<leaf id=",
> QUOTE(tree_leaf.id), " description=", QUOTE(tree_leaf.description), "
> />") AS xmlnode FROM tree_leaf) AS leaf ON tree_trunk.id =
> leaf.trunk_id
> GROUP BY tree_trunk.id) AS trunk
>
> Output (query does not format xml):
> <root>
> <trunk id='1' description='ab'>
> <leaf id='1' description='ab_aa' />
> </trunk>
> <trunk id='2' description='bc'>
> <leaf id='2' description='bc_aa' />
> <leaf id='3' description='bc_ab' />
> </trunk>
> <trunk id='3' description='cd'></trunk>
> <trunk id='4' description='de'></trunk>
> <trunk id='5' description='ef'>
> <leaf id='4' description='ef_aa' />
> </trunk>
> <trunk id='6' description='fg'></trunk>
> <trunk id='7' description='gh'>
> <leaf id='5' description='gh_aa' />
> </trunk>
> <trunk id='8' description='hi'>
> <leaf id='6' description='hi_aa' />
> </trunk>
> </root>
>
> ------
>
> Met vriendelijke groet,
>
> Arnold Daniels
> Bean IT
>
--
_______________________________________________________
Brian "Krow" Aker, brian at tangent.org
Seattle, Washington
http://krow.net/
http://tangent.org/
_______________________________________________________
You can't grep a dead tree.
