如何在Oracle 11g中使用XMLAGG函数序列化树数据而不复制带有嵌套结构的XML标记？

我有以下类型的树数据：1个主题，2个护照，2个地址，这是一个实体。如何使用嵌套的xml标签序列化为xml树数据？数据类型：

当我使用XMLAGG在Clob中构建xml时，我得到了带有重复标签的结构，例如：

<xml>
<person>
<title></title>
<document1></document1>
<document2></document2>
<adress1></adress1>
<adress2></adress2>
<adress1></adress1>
<phone1></phone1>
<phone2></phone2>
<phone3></phone3>
<phone1></phone1>
<phone2></phone2>
<phone3></phone3>
</person>
</xml> 

这是我对CLOB中的构建XML的查询：

    ---XMLPERSOM
SELECT XMLELEMENT ("Person",
       XMLELEMENT ("ReferenceCode", SBS.ReferenceCode),
       XMLELEMENT ("LastName", SBS.LastName),
       XMLELEMENT ("FirstName", SBS.FirstName),
       XMLELEMENT ("MiddleName", SBS.MiddleName),
       XMLELEMENT ("BirthDate", SBS.BirthDate),
       XMLELEMENT ("BirthPlace", SBS.BirthPlace),
       XMLELEMENT ("sourceCode", SBS.sourceCode),
       XMLELEMENT ("GroupCode", SBS.GroupCode),
--XMLDOCUMENTS       
       XMLELEMENT ("Documents",  
       XMLAGG(
       XMLELEMENT ("Document",
       XMLELEMENT ("Type", DCS.Type),
       XMLELEMENT ("Series", DCS.Series),
       XMLELEMENT ("Number", DCS.NumberID),
       XMLELEMENT ("IssueDate", DCS.IssueDate),
       XMLELEMENT ("IssueAuthority", DCS.IssueAuthority)))),

       XMLELEMENT ("Addresses",
       XMLAGG(
       XMLELEMENT ("Address",
       XMLELEMENT ("Type", ADDS.Type),
       XMLELEMENT ("Location", ADDS.Location),
       XMLELEMENT ("Street", ADDS.Street),
       XMLELEMENT ("PostalCode", ADDS.PostalCode),
       XMLELEMENT ("Country", ADDS.RU),
       XMLELEMENT ("Region", ADDS.Region)))), 
       )      

FROM SUBJECT_SEGMENT SBS
LEFT JOIN DOCUMENT_SEGMENT DCS ON SBS.ID = DCS.SUBJECT_ID
LEFT JOIN ADDRESS_SEGMENT ADDS ON SBS.ID = ADDS.SUBJECT_ID
GROUP BY SBS.ReferenceCode, 
         SBS.LastName, 
         SBS.FirstName, 
         SBS.MiddleName, 
         SBS.BirthDate, 
         SBS.BirthPlace,
         SBS.sourceCode,
         SBS.GroupCode

结果，我有重复的标签或重复的Clob xml。我需要一个Clob，并且没有重复的标签。感谢帮助！