How to achieve an outer join with existsNode() function

Question

I have a requirement to do an outer join with existsNode() function in my where clause. At present my where clause for join is like below
WHERE A.SOME_ID= “XYZ”
AND existsNode (B.SOMEXML_FEILD , …. ) = 1
AND existsNode (C.SOMEOTHERXML_FEILD , …. ) = 1
In this case if the existsNode fails on B or C, I still want data from A to be selected. How to rewrite this query to achieve that? I kinda want to achieve an outer join

Answer 1

Hi,
is this what you are looking for:
SQL> with t as(select 1 id1,'A' name from dual union all
  2            select 2 ,'B' name from dual union all
  3            select 3,'C' from dual)
  4      ,x as(select 1 id2,xmltype('<a>a</a>') xcol from dual union all
  5            select 2 ,xmltype('<b>b</b>') xcol from dual)
  6  select *
  7  from t,x
  8  where t.id1=x.id2(+)
  9    and (existsNode(x.xcol,'/a')=1 or x.xcol is null);
       ID1 N        ID2 XCOL                                                   
         1 A          1 <a>a</a>                                               
         3 C                                                                   
SQL> spool off;