XQuery (XPath) to count the child elements and group based on number's

Question

The sample XML files inputting and the expected output is at the bottom, need help to group based on the count of child elememts.

  <DashboardXML>
        <Column>
            <ColumnOrder>1</ColumnOrder>
            <ColLabel><![CDATA[test1]]></ColLabel>                
        </Column>
        <Column>
            <ColumnOrder>2</ColumnOrder>
            <ColLabel><![CDATA[t1est]]></ColLabel>       
        </Column>
          <Column>
            <ColumnOrder>3</ColumnOrder>
            <ColLabel><![CDATA[terst]]></ColLabel>       
        </Column>
    </DashboardXML>
    <DashboardXML>
        <Column>
            <ColumnOrder>1</ColumnOrder>
            <ColLabel><![CDATA[test1]]></ColLabel>                
        </Column>
        <Column>
            <ColumnOrder>2</ColumnOrder>
            <ColLabel><![CDATA[t1est]]></ColLabel>       
        </Column>
          <Column>
            <ColumnOrder>3</ColumnOrder>
            <ColLabel><![CDATA[terst]]></ColLabel>       
        </Column>
    </DashboardXML>
    <DashboardXML>
        <Column>
            <ColumnOrder>1</ColumnOrder>
            <ColLabel><![CDATA[test1]]></ColLabel>                
        </Column>
        <Column>
            <ColumnOrder>2</ColumnOrder>
            <ColLabel><![CDATA[t1est]]></ColLabel>       
        </Column>
    </DashboardXML>
    <DashboardXML>
        <Column>
            <ColumnOrder>1</ColumnOrder>
            <ColLabel><![CDATA[test1]]></ColLabel>                
        </Column>
        <Column>
            <ColumnOrder>2</ColumnOrder>
            <ColLabel><![CDATA[t1est]]></ColLabel>       
        </Column>
        <Column>
            <ColumnOrder>1</ColumnOrder>
            <ColLabel><![CDATA[test1]]></ColLabel>                
        </Column>
        <Column>
            <ColumnOrder>2</ColumnOrder>
            <ColLabel><![CDATA[t1est]]></ColLabel>       
        </Column>
    </DashboardXML>
    <DashboardXML>
        <Column>
            <ColumnOrder>1</ColumnOrder>
            <ColLabel><![CDATA[test1]]></ColLabel>                
        </Column>
        <Column>
            <ColumnOrder>2</ColumnOrder>
            <ColLabel><![CDATA[t1est]]></ColLabel>       
        </Column>
    </DashboardXML>

Above is the sample XML's as input and below is the XQuery:

for $b in /DashboardXML where count($b/Column) > 0 order by count($b/Column) return <li>{count($b/Column)} </li>

The query yields the below output (sample):

    <li>3</li>
    <li>3</li>
    <li>2</li>
    <li>4</li>
    <li>2</li>

Now the question is how to group the output like Below:

2 = 2 (counts)
3 = 2 (counts)
4 = 1 (counts)

Answer 1

Given you're using an XQuery 3.0 capable query processor, use the group by clause.

for $b in $xml/DashboardXML
let $count := count($b/Column)
where $count > 0
order by $count descending
group by $count
return <li>{$b/DashboardName/text()} = {$count} ({count ($b) }) </li>

Which will output

<li> = 1 (1) </li>
<li> = 2 (2) </li>

for the input given (notice the missing DashboardName elements and that I changed the where clause to allow any non-zero number of Column children).