Where clause as a string in a table - how can i use...

Question

Table Name : WhereTable
=======================
QueryNo          WhereClause
101          '&student.rno = 10 and &class.cid = 20'
202          ..........
I have some other tables and I joined all those to prepare a query.
From the above query I get QueryNo.
Based that query no. I need to fetch the where clause from the WhereTable.
Then I need to use this where clause in this query itself to filter more.
How can I do this.
Please dont suggest PLSQL blocks for this, as I need to create a view with this query.
It is something like this:
select some_result from student, class, WhereTable
where student.cid = class.cid and
student.QueryNo = WhereTable.QueryNo and
WhereTable.WhereClause

Answer 1

Not sure about your actual requirements but here is something to play with:
michaels>  create table wheretable (queryno, whereclause)
as select 1, '&emp.empno = 7788 and &dept.deptno = 20' from dual
Table created.
michaels>  select t.* from wheretable, xmltable('.' passing dbms_xmlgen.getxmltype('select empno,emp.deptno,dname
                     from dept, emp, wheretable
                    where dept.deptno = emp.deptno and queryno = 1 and ' || replace(whereclause,chr(38))).extract('ROWSET/ROW')
                                         columns empno      integer path 'EMPNO',
                                                 deptno     integer path 'DEPTNO',
                                                 dname varchar2(10) path 'DNAME') t
     EMPNO     DEPTNO DNAME    
      7788         20 RESEARCH