Question { CTS, 22574 }

How many LONG columns are allowed in a table?

Answer

only 1 Long columns allowed in table

Question { Temenos, 61292 }

I have student marks in a student table. I need second
highest mark .Then what will the query for this?

Answer

select max(mark) from student where mark <
(select max(mark)from student)

Question { 7087 }

When the mutating error will comes? and how it will be
resolved?

Answer

Mutating error in Trigger:-
When programmer create trigger and give table name abc and
in body if programmer is using same table abc for
selecting,updating,deleting,inserting then mutation occur.
ex.:-
create or replace trigger xyz
after
update
on abc
for each row
referencing :OLD as OLD :NEW as NEW
begin
select max(salary) from abc;

update abc
set location_id=:NEW.location_id
where dept_id=105;

end;
------------------------------------------------------------
In the above example you are updating same table which is
under transaction so mutation problem occur here.

Solution on this is
You can use Temporary table or Materialize view which can
solve above problem