比较yyyymmdd格式的XSLT 1.0中的日期

<xsl:template match="/">
  <xsl:variable name="date1" select="'20220101'" />
  <xsl:variable name="date2" select="'20220115'" />
  
  <xsl:choose>
    <xsl:when test="number(substring($date1, 1, 4)) &gt; number(substring($date2, 1, 4))">
      <xsl:text>Date 1 is later than Date 2</xsl:text>
    </xsl:when>
    <xsl:when test="number(substring($date1, 1, 4)) &lt; number(substring($date2, 1, 4))">
      <xsl:text>Date 1 is earlier than Date 2</xsl:text>
    </xsl:when>
    <xsl:when test="number(substring($date1, 5, 2)) &gt; number(substring($date2, 5, 2))">
      <xsl:text>Date 1 is later than Date 2</xsl:text>
    </xsl:when>
    <xsl:when test="number(substring($date1, 5, 2)) &lt; number(substring($date2, 5, 2))">
      <xsl:text>Date 1 is earlier than Date 2</xsl:text>
    </xsl:when>
    <xsl:when test="number(substring($date1, 7, 2)) &gt; number(substring($date2, 7, 2))">
      <xsl:text>Date 1 is later than Date 2</xsl:text>
    </xsl:when>
    <xsl:when test="number(substring($date1, 7, 2)) &lt; number(substring($date2, 7, 2))">
      <xsl:text>Date 1 is earlier than Date 2</xsl:text>
    </xsl:when>
    <xsl:otherwise>
      <xsl:text>Date 1 is the same as Date 2</xsl:text>
    </xsl:otherwise>
  </xsl:choose>
</xsl:template>