View on materialized view giving error while selection

Question

Hello Guys,
My Oracle DB is 11gR1, Enterprise Linux is the operating system.
I have a materialized view in my schema, if described this is the output:
term_id          number(10)
class_id     varchar2(4)
section_id     number(10)
acad_year_id     number(10)
subject_id     number(10)
branch_id     number(10)
paper_id     number(10)
student_id     number(10)
calc_out_of     float(53)
obtain_std_marks     float(53)
rep_comp_id     number(10)
grade          varchar2(4)
sum_std_marks     number(10)
teacher_remarks     varchar2(201)
sum_exam_marks     number(10)
updt_user     number(10)
updt_time     date
entry_user_id     number(10)
absent_rsn     number(10)
entry_date     date
I am creating a view on this materialized view, this is the statement
create or replace view bssdata.sta_mis_view as
select
to_number("acad_year_id") acad_year_id,
to_number("term_id") term_id,
"class_id",
to_number("section_id") section_id,
to_number("subject_id") subject_id,
to_number("branch_id") branch_id,
to_number("student_id") student_id,
--null as field_to_be_used,
to_number(sum("obtain_std_marks")) as obtained_marks,
to_number(sum("calc_out_of")) as total_marks,
to_number(round(sum("obtain_std_marks")) / to_number(sum("calc_out_of")*100,2)) as percentage
from bssdata.mv_sta_std_result
where "acad_year_id" = 18 and "term_id" = 2
group by to_number("acad_year_id"), to_number("term_id"), "class_id", to_number("section_id"), to_number("subject_id"), to_number("branch_id"), to_number("student_id")
having to_number(sum("obtain_std_marks")) > 0 or to_number(sum("calc_out_of")) >= 5
View is created.
But when i try to select from this view, it gives different errors:
This is the error I am facing right now:
SQL Error: ORA-01481: invalid number format model
01481. 00000 - "invalid number format model"
*Cause:    The user is attempting to either convert a number to a string via TO_CHAR or a string to a number via TO_NUMBER and has
supplied an invalid number format model parameter
There is a problem with datatype and double quotes that I am not able to understand so far. Please guide if someone has faced the same problem and have solution.
Regards, Imran

Answer 1

SQL Error: ORA-01481: invalid number format model
+01481. 00000 - "invalid number format model"+
*Cause: The user is attempting to either convert a number to a string via TO_CHAR or a string to a number via TO_NUMBER and has+
supplied an invalid number format model parameter
View can create and there are may no problems.But you when execute "select * from bssdata.sta_mis_view" statement oracle automatically there convert some types to others(varchar=>number,number=>varchar),thus problem there.For example to_number('3sfss')? how can convert this?,because of this you got an error.See below example.
SQL*Plus: Release 10.2.0.2.0 - Production on Fri Jun 25 11:15:47 2010
Copyright (c) 1982, 2005, Oracle.  All Rights Reserved.
Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.2.0 - Production
With the Partitioning, OLAP and Data Mining options
SQL> create view v_test1 as select * from  (
  2  select '1' as n from dual
  3  union
  4  select '2w' as n from dual);
View created.
SQL> create view v_test2 as
  2  select to_number(n) as n1 from v_test1;
View created.
SQL> select * from v_test2;
ERROR:
ORA-01722: invalid number
no rows selected
SQL>