Need help for SQL SELECT query to fetch XML records from Oracle tables having CLOB field

Question

Hello,
I have a scenario wherein i need to fetch records from several oracle tables having CLOB fields(which is holding XML) and then merge them logically to form a hierarchy XML. All these tables are related with PK-FK relationship. This XML hierarchy is having 'OP' as top-most root node and ‘DE’ as it’s bottom-most node with One-To-Many relationship. Hence, Each OP can have multiple GM, Each GM can have multiple DM and so on.
Table structures are mentioned below:
OP:
Name                             Null                    Type        
OP_NBR                    NOT NULL      NUMBER(4)    (Primary Key)
OP_DESC                                        VARCHAR2(50)
OP_PAYLOD_XML                           CLOB       
GM:
Name                          Null                   Type        
GM_NBR                  NOT NULL       NUMBER(4)    (Primary Key)
GM_DESC                                       VARCHAR2(40)
OP_NBR               NOT NULL          NUMBER(4)    (Foreign Key)
GM_PAYLOD_XML                          CLOB   
DM:
Name                          Null                    Type        
DM_NBR                  NOT NULL         NUMBER(4)    (Primary Key)
DM_DESC                                         VARCHAR2(40)
GM_NBR                  NOT NULL         NUMBER(4)    (Foreign Key)
DM_PAYLOD_XML                            CLOB       
DE:
Name                          Null                    Type        
DE_NBR                     NOT NULL           NUMBER(4)    (Primary Key)
DE_DESC                   NOT NULL           VARCHAR2(40)
DM_NBR                    NOT NULL           NUMBER(4)    (Foreign Key)
DE_PAYLOD_XML                                CLOB    
+++++++++++++++++++++++++++++++++++++++++++++++++++++
SELECT
j.op_nbr||'||'||j.op_desc||'||'||j.op_paylod_xml AS op_paylod_xml,
i.gm_nbr||'||'||i.gm_desc||'||'||i.gm_paylod_xml AS gm_paylod_xml,
h.dm_nbr||'||'||h.dm_desc||'||'||h.dm_paylod_xml AS dm_paylod_xml,
g.de_nbr||'||'||g.de_desc||'||'||g.de_paylod_xml AS de_paylod_xml,
FROM
DE g, DM h, GM i, OP j
WHERE
h.dm_nbr = g.dm_nbr(+) and
i.gm_nbr = h.gm_nbr(+) and
j.op_nbr = i.op_nbr(+)
+++++++++++++++++++++++++++++++++++++++++++++++++++++
I am using above SQL select statement for fetching the XML records and this gives me all related xmls for each entity in a single record(OP, GM, DM. DE). Output of this SQL query is as below:
Current O/P:
<resultSet>
     <Record1>
          <OP_PAYLOD_XML1>
          <GM_PAYLOD_XML1>
          <DM_PAYLOD_XML1>
          <DE_PAYLOD_XML1>
     </Record1>
     <Record2>
          <OP_PAYLOD_XML2>
          <GM_PAYLOD_XML2>
          <DM_PAYLOD_XML2>
          <DE_PAYLOD_XML2>
     </Record2>
     <RecordN>
          <OP_PAYLOD_XMLN>
          <GM_PAYLOD_XMLN>
          <DM_PAYLOD_XMLN>
          <DE_PAYLOD_XMLN>
     </RecordN>
</resultSet>
Now i want to change my SQL query so that i get following output structure:
<resultSet>
     <Record>
          <OP_PAYLOD_XML1>
          <GM_PAYLOD_XML1>
          <GM_PAYLOD_XML2> .......
          <GM_PAYLOD_XMLN>
          <DM_PAYLOD_XML1>
          <DM_PAYLOD_XML2> .......
          <DM_PAYLOD_XMLN>
          <DE_PAYLOD_XML1>
          <DE_PAYLOD_XML2> .......
          <DE_PAYLOD_XMLN>
     </Record>
     <Record>
          <OP_PAYLOD_XML2>
          <GM_PAYLOD_XML1'>
          <GM_PAYLOD_XML2'> .......
          <GM_PAYLOD_XMLN'>
          <DM_PAYLOD_XML1'>
          <DM_PAYLOD_XML2'> .......
          <DM_PAYLOD_XMLN'>
          <DE_PAYLOD_XML1'>
          <DE_PAYLOD_XML2'> .......
          <DE_PAYLOD_XMLN'>
     </Record>
<resultSet>
Appreciate your help in this regard!

Answer 1

Hi,
A few questions :
How's your first query supposed to give you an XML output like you show ?
Is there something you're not telling us?
What's the content of, for example, <OP_PAYLOD_XML1> ?
I don't think it's a good idea to embed the node level in the tag name, it would make much sense to expose that as an attribute.
What's the db version BTW?