How to allow for ampersand in XMLtable()?

Question

Starting with this Q&A, note that while this works:

with data as (
  select 'Hallöle slovenĈina Hallöle slovenđina' str from dual
)
select a.str, b.str2
from data a, xmltable( '/'
  passing xmltype( '<dat>' || a.str || '</dat>' )
  columns
   str2 varchar2(4000) path '/dat'
) b

… this fails (note the addition of "AT&T and AT & T" to the string):

with data as (
  select 'Hallöle AT&T and AT & T slovenĈina Hallöle slovenđina' str from dual
)
select a.str, b.str2
from data a, xmltable( '/'
  passing xmltype( '<dat>' || a.str || '</dat>' )
  columns
   str2 varchar2(4000) path '/dat'
) b

with error message:

ORA-31011: XML parsing failed
ORA-19202: Error occurred in XML processing
LPX-00242: invalid use of ampersand ('&') character (use &)
Error at line 2
31011. 00000 -  "XML parsing failed"
*Cause:    XML parser returned an error while trying to parse the document.
*Action:   Check if the document to be parsed is valid.

How to fix?

---

First crude attempt(s):

replace('Hallöle AT&T and AT & T slovenĈina Hallöle slovenđina', ' & ', ' and ') 

While this works (at least for "AT & T", it would be desirable to preserve the ampersand in the final output…

Answer 1

Using '&\2' as replacement string, backreferencing the 2nd ( ) group:

with data as (
  select 'Hallöle AT&T and AT & T slovenĈina Hallöle slovenđina' str from dual
)
select a.str, b.str2
from data a, xmltable( '/'
  passing xmltype( '<dat>' || regexp_replace(a.str,'(&)([^#])','&38;\2') || '</dat>' )
  columns
   str2 varchar2(4000) path '/dat'
) b

Answer 2

The error message clearly told you to use &.

with data as (
  select 'Hallöle AT&T and AT & T slovenĈina Hallöle slovenđina' str from dual
)
select a.str, b.str2
from data a, xmltable( '/'
  passing xmltype( '<dat>' || a.str || '</dat>' )
  columns
   str2 varchar2(4000) path '/dat'
) b
;

STR
-------------------------------------------------------------------------
STR2
--------------------------------------------------------------------------------
Hallöle AT&amp;T and AT &amp; T sloven&#264;ina Hallöle sloven&#273;ina
Hallöle AT&T and AT & T slovenĈina Hallöle slovenđina

Update (will not work for other special characters such as >):

with data as (
  select regexp_replace('Hallöle AT&T and AT & T slovenĈina Hallöle slovenđina', '(&)([^#])', '\1amp;\2') str from dual
)
select a.str, b.str2
from data a, xmltable( '/'
  passing xmltype( '<dat>' || a.str || '</dat>' )
  columns
   str2 varchar2(4000) path '/dat'
) b
;

STR
-------------------------------------------------------------------------
STR2
--------------------------------------------------------------------------------
Hallöle AT&amp;T and AT &amp; T sloven&#264;ina Hallöle sloven&#273;ina
Hallöle AT&T and AT & T slovenĈina Hallöle slovenđina

Answer 3

I think the simplest solution is to use build-in function DBMS_XMLGEN.CONVERT:

with data as (
  select 'Hallöle slovenĈina Hallöle slovenđina' str from dual
)
select a.str, b.str2
from data a, xmltable( '/'
  passing xmltype( '<dat>' || DBMS_XMLGEN.CONVERT(a.str,0) || '</dat>' )
  columns
   str2 varchar2(4000) path '/dat'
) b

Function HTF.ESCAPE_SC should also work.