text: --ex01.
  select*from dept_test;
  create table dept_test(
  dno number(2),
  dname varchar2(14),
  loc varchar2(13)
  );
  
  --ex02.
  select*from emp_test;
  create table emp_test(
  eno number(4),
  ename varchar2(10),
  dno number(2)
  );
  
  --ex03.
  alter table emp_test modify ename varchar2(25);
  
  --ex04.
  select*from EMPLOYEE2;
  create table EMPLOYEE2 (emd_id,name,sal,dept_id)
  as select eno,ename,salary,dno from EMPLOYEE;
  
  --ex05.
  select*from emp_test;
  drop table emp_test;
  
  --ex06.
  select*from emp_test;
  rename employee2 to emp_test;
  
  --ex07.
  select*from dept_test;
  alter table dept_test drop column dname;
  
  --ex08.
  alter table dept_test set unused column loc;
  
  --ex09.
  alter table dept_test drop unused columns;