Hierarchial query output as xml

Question

Pls find below sample table script and desired output format.XML output should maintain the hierarchy info which is the requirement.Also is it possible to do in single sql.
Thanks.
CREATE TABLE MAIN
ID NUMBER,
NAME VARCHAR2(20 BYTE)
INSERT INTO MAIN ( ID, NAME ) VALUES (
1, 'OS');
INSERT INTO MAIN ( ID, NAME ) VALUES (
2, 'Windows');
INSERT INTO MAIN ( ID, NAME ) VALUES (
3, 'DOS');
INSERT INTO MAIN ( ID, NAME ) VALUES (
4, '1.x');
INSERT INTO MAIN ( ID, NAME ) VALUES (
5, '1.1.x');
INSERT INTO MAIN ( ID, NAME ) VALUES (
7, '1.1.1.1');
INSERT INTO MAIN ( ID, NAME ) VALUES (
8, '1.2');
INSERT INTO MAIN ( ID, NAME ) VALUES (
9, '2.x');
INSERT INTO MAIN ( ID, NAME ) VALUES (
10, '2.1');
INSERT INTO MAIN ( ID, NAME ) VALUES (
11, '2.2');
INSERT INTO MAIN ( ID, NAME ) VALUES (
12, '2.2.1');
INSERT INTO MAIN ( ID, NAME ) VALUES (
13, '2.2.2');
COMMIT;
CREATE TABLE RELA
REL_ID NUMBER,
ID NUMBER,
PARENT_REL_ID NUMBER
INSERT INTO RELA ( REL_ID, ID, PARENT_REL_ID ) VALUES (
1, 1, NULL);
INSERT INTO RELA ( REL_ID, ID, PARENT_REL_ID ) VALUES (
2, 2, 1);
INSERT INTO RELA ( REL_ID, ID, PARENT_REL_ID ) VALUES (
3, 4, 2);
INSERT INTO RELA ( REL_ID, ID, PARENT_REL_ID ) VALUES (
4, 5, 3);
INSERT INTO RELA ( REL_ID, ID, PARENT_REL_ID ) VALUES (
5, 7, 4);
INSERT INTO RELA ( REL_ID, ID, PARENT_REL_ID ) VALUES (
6, 8, 4);
INSERT INTO RELA ( REL_ID, ID, PARENT_REL_ID ) VALUES (
7, 9, 2);
INSERT INTO RELA ( REL_ID, ID, PARENT_REL_ID ) VALUES (
8, 10, 7);
INSERT INTO RELA ( REL_ID, ID, PARENT_REL_ID ) VALUES (
12, 7, 11);
INSERT INTO RELA ( REL_ID, ID, PARENT_REL_ID ) VALUES (
14, 9, 9);
INSERT INTO RELA ( REL_ID, ID, PARENT_REL_ID ) VALUES (
15, 10, 14);
INSERT INTO RELA ( REL_ID, ID, PARENT_REL_ID ) VALUES (
9, 3, 1);
INSERT INTO RELA ( REL_ID, ID, PARENT_REL_ID ) VALUES (
10, 4, 9);
INSERT INTO RELA ( REL_ID, ID, PARENT_REL_ID ) VALUES (
11, 5, 10);
INSERT INTO RELA ( REL_ID, ID, PARENT_REL_ID ) VALUES (
16, 11, 14);
INSERT INTO RELA ( REL_ID, ID, PARENT_REL_ID ) VALUES (
13, 8, 10);
INSERT INTO RELA ( REL_ID, ID, PARENT_REL_ID ) VALUES (
17, 12, 16);
INSERT INTO RELA ( REL_ID, ID, PARENT_REL_ID ) VALUES (
18, 13, 16);
COMMIT;
Sample Query
select rel_id,level,lpad(' ',5*level)||name,
xmlelement("rel_id", XMLAttributes(name as "name",rel_id as "rel_id")) as val
from main , rela
where main.id=rela.id
start with parent_rel_id is null
connect by prior rel_id=parent_rel_id;
Required xml output
Required xml output
<1 name="OS" >
<2 name="Windows">
<3 name="1.x" 3>
<4 name="1.1.x">
<5 name="1.1.1.1"></5>
<6 name="1.2"></6>
</4>
</3>
<7 name="2.x" >
<8 name="2.1" ></8>
</7>
</2>
<9 name="DOS" >
<14 name="2.x" >
<15 name="2.1" ></15>
<16 name="2.2">
<17 name="2.2.1" ></17>
<18 name="2.2.2" ></18>
</16>
</14>
<10 name="1.x" >
<11 name="1.1.x" >
<12 name="1.1.1.1" ></12>
</11>
<13 name="1.2" >
</13>
</10>
</9>
<1>
Edited by: ravit on Sep 18, 2009 4:47 PM
Edited by: ravit on Sep 19, 2009 9:53 AM

Answer 1

Numbers (or names that start with numbers) are generally not allowed as tag names:
SQL> select xmltype('<1></1>') xml from dual
select xmltype('<1></1>') xml from dual
Error at line 1
ORA-31011: XML parsing failed
ORA-19202: Error occurred in XML processing
LPX-00231: invalid character 49 ('1') found in a Name or Nmtoken
Error at line 1
ORA-06512: at "SYS.XMLTYPE", line 310
ORA-06512: at line 1So what you can do is e.g.:
SQL> set echo on
SQL> set pages 5000
SQL> select trim (column_value) xml
  from xmltable ('.' passing dbms_xmlgen.getxmltype (dbms_xmlgen.
                 newcontextfromhierarchy (
                 'select level, xmlelement (evalname ''r'' || rel_id, xmlattributes(name "name")) name
      from main, rela
     where main.id = rela.id
start with parent_rel_id is null
connect by prior rel_id = parent_rel_id'
XML                                                                            
<?xml version="1.0"?>                                                          
<r1 name="OS">                                                                 
  <r2 name="Windows">                                                          
    <r3 name="1.x">                                                            
      <r4 name="1.1.x">                                                        
        <r5 name="1.1.1.1"/>                                                   
        <r6 name="1.2"/>                                                       
      </r4>                                                                    
    </r3>                                                                      
    <r7 name="2.x">                                                            
      <r8 name="2.1"/>                                                         
    </r7>                                                                      
  </r2>                                                                        
  <r9 name="DOS">                                                              
    <r10 name="1.x">                                                           
      <r11 name="1.1.x">                                                       
        <r12 name="1.1.1.1"/>                                                  
      </r11>                                                                   
      <r13 name="1.2"/>                                                        
    </r10>                                                                     
    <r14 name="2.x">                                                           
      <r15 name="2.1"/>                                                        
      <r16 name="2.2">                                                         
        <r17 name="2.2.1"/>                                                    
        <r18 name="2.2.2"/>                                                    
      </r16>                                                                   
    </r14>                                                                     
  </r9>                                                                        
</r1>                                                                          
1 row selected.