如何在Oracle PLSQL中获得一个自动关闭的xml标签？

DECLARE
  xml_data XMLType;
BEGIN
  xml_data := XMLType('<root><tag>data</tag></root>');
  -- 或者从表中获取XML数据
  -- SELECT xml_column INTO xml_data FROM your_table WHERE condition;
END;

DECLARE
  xml_data XMLType;
  doc_fragment DBMS_XMLDOM.DOMDocumentFragment;
BEGIN
  xml_data := XMLType('<root><tag>data</tag></root>');
  doc_fragment := DBMS_XMLDOM.newDOMDocumentFragment(xml_data);
END;

DECLARE
  xml_data XMLType;
  doc_fragment DBMS_XMLDOM.DOMDocumentFragment;
  text_node DBMS_XMLDOM.DOMText;
BEGIN
  xml_data := XMLType('<root><tag>data</tag></root>');
  doc_fragment := DBMS_XMLDOM.newDOMDocumentFragment(xml_data);
  
  text_node := DBMS_XMLDOM.createTextNode('</tag>');
  DBMS_XMLDOM.appendChild(doc_fragment, text_node);
END;

DECLARE
  xml_data XMLType;
  doc_fragment DBMS_XMLDOM.DOMDocumentFragment;
  text_node DBMS_XMLDOM.DOMText;
  xml_string VARCHAR2(4000);
BEGIN
  xml_data := XMLType('<root><tag>data</tag></root>');
  doc_fragment := DBMS_XMLDOM.newDOMDocumentFragment(xml_data);
  
  text_node := DBMS_XMLDOM.createTextNode('</tag>');
  DBMS_XMLDOM.appendChild(doc_fragment, text_node);
  
  xml_string := DBMS_XMLDOM.getXMLType(doc_fragment).getStringVal();
  DBMS_OUTPUT.put_line(xml_string);
END;

<root><tag>data</tag></root></tag>