[xsl] saxon with sql extension and attribute template values

[Georges Schmitz <georges.schmitz@xxxxxxxxx>]

I'm using saxon8-9-0-3j in combination with the sql extension. But using 
it in a more dynamic way (providing the sql select components by 
variables or parameters) doesn't work. In the documentation Michael Kay 
declares the query attributes as being "attribute value templates", but 
I just get expected results, when I use literal values. It doesn't work 
either with an xsl:attribute declaration (see "row-tag").

     <xsl:variable name="table" as="xs:string">tc_ad</xsl:variable>
     <xsl:variable name="cols" 
as="xs:string">id,nationalidnr,subject</xsl:variable>
     <sql:query connection="$connection" table="{$table}" 
column="{$cols}" column-tag="col" >
       <xsl:attribute name="row-tag">
         <xsl:value-of select="$table"/>
       </xsl:attribute>
     </sql:query>


So what am I missing, or is the sql extension really just a show case 
(Michael Kay warns the user at the beginning of the description that it 
is not "production-quality")?

Thanks,
Georges