[xquery-talk] Wild Card in 'Where' Clause

[Michael Kay]

Use

where $brunch = ($alum/@brunch, "either") and 
      $intl = ($alum/@intl, "either")

Michael Kay
http://www.saxonica.com/ 

> -----Original Message-----
> From: talk-bounces at xquery.com 
> [mailto:talk-bounces at xquery.com] On Behalf Of McAuley, Grant (LLU)
> Sent: 25 August 2005 20:54
> To: talk at xquery.com
> Subject: [xquery-talk] Wild Card in 'Where' Clause
> 
> 
> ///Xml fragment://///////////////////// 
> 
> <alumnus brunch="yes" intl="no">
>   <name>Sally Smith</name>
> </alumnus>
> 
> 
> ///XQuery function:////////////////////
> 
> declare function local:getTableRows($brunch as xs:string, $intl as
> xs:string) as element()* {
> 
>   let $col := collection(" ... ")
>   for $alum in $col/alumnus
>   where ($alum[@brunch = $brunch] and $alum[@intl = $intl])
>   return
>    <tr>
>      <td>{ $alum/name/text() }</td>
>    </tr>
> 
> };
> 
> 
> For the xml fragment above the 'brunch' and 'intl' attributes can take
> values of 'yes' or 'no'.  However, I would like to be able to pass
> 'either' to $intl and $brunch in the xquery function, so that 
> my results
> can show e.g., fragments where the 'intl' attribute is either 'yes' or
> 'no' and 'brunch' is 'yes' (using this call: getTableRows("either",
> "yes")).  The problem is that 'either' is not in the xml.
> 
> One way to do this is to use a 'where' clause like:
> 
>  where ($alum[@brunch = $brunch] and $alum[@intl = $intl]) or
> 	 ($alum[@brunch = $brunch] and $intl = 'either') or
> 	 ($brunch = 'either' and $alum[@intl = $intl]) or
> 	 ($brunch = 'either' and $intl = 'either')
> 
> This seems to work but if I have to add another 'either'/'something'
> condition this will get even more ugly.
> 
> So my question (finally):
> 
> 1) Is there some kind of 'wildcard' construct I could use in the where
> clause?  Something resulting in:
> 	where $alum[@brunch = 'yes'] and $alum[@intl = '*'] (via
> getTableRow('yes', '*')), so that no tuples fill be filtered based on
> the 'intl' attribute?  In other words, here '*' has the meaning such
> that '$alum[@intl = '*']' pass all fragments whatever the value of the
> 'intl' attribute.
> 
> 2) If not, is there a better way to do this? 
> 
> Any help would be appreciated.
> 
> 
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