-- 1. PL/SQL 에서 Execute Immediate 를 이용.
DECLARE
    x VARCHAR2(100) := '(3*2 +3) / 3';
    y NUMBER;
BEGIN
    EXECUTE IMMEDIATE('SELECT '||x||' FROM dual') INTO y;
    dbms_output.put_line(x||' = '||y);
END;
/

-- 2. SQL 에서 dbms_xmlgen 을 이용.
SELECT x
     , TO_NUMBER(
       dbms_xmlgen.getxmltype(
       'SELECT '||x||' FROM dual'
       ).Extract('//text()')
       ) y
  FROM (SELECT '(3*2 +3) / 3' x FROM dual)
;