(:
   file:    list_vars_by_numYears.xq
   date:    13-July-2010
   author:  Gary Lewis
   purpose: Lists IPEDS directory variables by the number of years that the variables have appeared in
            IPEDS surveys. Includes name, number of years, first year, last year, and description of the
            variable in the last year. Used to help identify variables for possible inclusion in the
            data warehouse.
   usage:   Can be run from any location.
   example: zorba -f -q list_vars_by_numYears.xq -o list_vars_by_numYears.xml -z indent=yes
:)

<results>
{
for $i in fn:doc("../xml/metadata/ipedsVars_metadata.xml")/variables/var
let $name := $i/@name,
    $numYears := xs:integer($i/@numYears),
    $firstYear := min(fn:doc("../xml/metadata/ipedsVars_metadata.xml")/variables/var[@name =  $name]/detail/@year),
    $lastYear := max(fn:doc("../xml/metadata/ipedsVars_metadata.xml")/variables/var[@name =  $name]/detail/@year),
    $lastYrDesc := fn:doc("../xml/metadata/ipedsVars_metadata.xml")/variables/var[@name = $name]/detail[@year = $lastYear]/@description
order by
    $numYears descending,
    $name ascending
return <var name="{$name}" numYears="{$numYears}" firstYear="{$firstYear}" lastYear="{$lastYear}" lastYrDesc="{$lastYrDesc}" />
}
</results>