Question

I have the following xml:

<RowSet>
  <Row>
    <Number>12345</Number>
    <Quantity>42</Quantity>
  </Row>
  <Row>
    <Number>12345</Number>
    <Quantity>12</Quantity>
  </Row>
  <Row>
    <Number>54321</Number>
    <Quantity>37</Quantity>
  </Row>
</RowSet>

I want to use an xsl to combine the elements with the same Number and the resulting should sum the Quantity elements. So the output should look like this:

<RowSet>
  <Row>
    <Number>12345</Number>
    <Quantity>64</Quantity>
  </Row>
  <Row>
    <Number>54321</Number>
    <Quantity>37</Quantity>
  </Row>
</RowSet>

Answer 1

<xsl:key name="kRow" match="Row" use="Number" />

<xsl:template match="RowSet">
  <xsl:copy>
    <xsl:apply-templates select="Row[
      generate-id() = generate-id(key('kRow', Number)[1])
    ]" />
  </xsl:copy>
</xsl:template>

<xsl:template match="Row">
  <xsl:copy>
    <xsl:copy-of select="Number" />
    <Quantity>
      <xsl:value-of select="sum(key('kRow', Number)/Quantity)" />
    </Quantity>
  </xsl:copy>
</xsl:template>