drop table emp ;

create table emp as select * from scott.emp;

variable mn number;
variable mx number;

begin
  :mn := 500;
  :mn := 100;
end;
/  

set autotrace traceonly;

select * from emp                 
where  sal between :mn and :mx;

alter session set optimizer_features_enable = '9.0.1';

select * from emp                 
where  sal between :mn and :mx;

analyze table emp compute statistics;

select * from emp                 
where  sal between :mn and :mx;

alter session set optimizer_features_enable = '8.1.7';

select * from emp                 
where  sal between :mn and :mx;




