Combine 2 tables in XML

Question

Table T1:
C1  C2  C3 
1   2   3  
10  20  30 
100 200 300 Table T2:
COL1 COL2
A    B   
AA   BB   Desired output:
<ROWSET>
     <T1>
          <C1>1</C1>
          <C2>2</C2>
          <C3>3</C3>
     </T1>
     <T1>
          <C1>10</C1>
          <C2>20</C2>
          <C3>30</C3>
     </T1>
     <T1>
          <C1>100</C1>
          <C2>200</C2>
          <C3>300</C3>
     </T1>
     <T2>
          <COL1>A</COL1>
          <COL2>B</COL2>
     </T2>
     <T2>
          <COL1>AA</COL1>
          <COL2>BB</COL2>
     </T2>
</ROWSET>Please, help. Thanks.
with t1 as
select '1' c1, '2' c2, '3' c3 from dual
union
select '10' , '20' , '30' from dual
union
select '100' , '200' , '300' from dual
, t2 as
select 'A' col1, 'B' col2 from dual
union
select 'AA' , 'BB' from dual
select ...

Answer 1

Here's one way:
SQL>  with t1 as
select '1' c1, '2' c2, '3' c3 from dual union all
select '10' , '20' , '30' from dual union all
select '100' , '200' , '300' from dual
, t2 as
select 'A' col1, 'B' col2 from dual union all
select 'AA' , 'BB' from dual
select xmlserialize(content sys_xmlagg(x) indent) x from (
select xmlelement("T1", sys_xmlgen(c1), sys_xmlgen(c2), sys_xmlgen(c3)) x from t1
  union all
select xmlelement("T2", sys_xmlgen(col1), sys_xmlgen(col2)) from t2
X                            
<?xml version="1.0"?>        
<ROWSET>                     
  <T1>                       
    <C1>1</C1>               
    <C2>2</C2>               
    <C3>3</C3>               
  </T1>                      
  <T1>                       
    <C1>10</C1>              
    <C2>20</C2>              
    <C3>30</C3>              
  </T1>                      
  <T1>                       
    <C1>100</C1>             
    <C2>200</C2>             
    <C3>300</C3>             
  </T1>                      
  <T2>                       
    <COL1>A</COL1>           
    <COL2>B</COL2>           
  </T2>                      
  <T2>                       
    <COL1>AA</COL1>          
    <COL2>BB</COL2>          
  </T2>                      
</ROWSET>                    
1 row selected.Note: xmlserialize is just for formatting the output and not neccessary in general.