Oracle XMLSERIALIZE动态顺序by语句

select VL_或者D_XML2('或者DID DESC') FROM DUAL;

select VL_或者D_XML2(null) FROM DUAL;

create or replace FUNCTION VL_或者D_XML2 (
      或者DER_BY_IN VARCHAR2
)
      
RETURN clob IS
ret_val clob;

BEGIN
  DECLARE 
  或者DER_STATEMENT VARCHAR2(1000);
  V_SQL VARCHAR2(3000);
  
  BEGIN
  IF 或者DER_BY_IN IS NULL 或者 或者DER_BY_IN = '' THEN
    或者DER_STATEMENT := ' 或者DID DESC';
  ELSE  
    或者DER_STATEMENT := 或者DER_BY_IN;
  END IF;
  
  SELECT 
  'BEGIN SELECT XMLSERIALIZE(CONTENT XMLROOT(
          XMLELEMENT("TEST", XMLAGG(
            XMLELEMENT("TEST_ELEMENT", 
              XMLF或者EST(  o.或者DID, 
                          o.PATIENT_FIRSTNAME, 
                          o.PATIENT_SURNAME)))), VERSION ''1.0'', STANDALONE YES)) 
                          INTO :ret_val FROM (SELECT * FROM OE或者D WHERE SRCHPATTERN LIKE ''%MARKUS%'' AND SRCHPATTERN LIKE ''%FISCHER%'' 或者DER BY :或者DER_STATEMENT) o;END;' INTO V_SQL FROM DUAL;
   
    EXECUTE IMMEDIATE V_SQL using OUT ret_val, IN 或者DER_STATEMENT;
                  
    return ret_val;
END;
END;

open cur for 'select * from t order by :val' using 'y'

select * from t order by 'y'

create table t as 
  select level x, 11-level y from dual
  connect by level <= 10;
  
var cur refcursor;

begin
  open :cur for
    'select * from t order by :val' using 'y';
end;
/

print :cur

         X          Y
---------- ----------
         1         10
         2          9
         3          8
         4          7
         5          6
         6          5
         7          4
         8          3
         9          2
        10          1