text: create table EMPLOYEES (  
    empno             number,  
    name              varchar2(50) not null,  
    job               varchar2(50),  
    manager           number,  
    hiredate          date,  
    salary            number(7,2),  
    commission        number(7,2),  
    deptno           number,  
    constraint pk_employees primary key (empno),  
    constraint fk_employees_deptno foreign key (deptno) 
        references DEPARTMENTS (deptno)  
  );
  /
  
  INSERT ALL
    into employees values(2, 'Abdul Azeez', 'Head of Developers', 1, TO_DATE('2019/01/12', 'yyyy/mm/dd'), 100000, 20000, 1)
    into employees values(3, 'Yazid', 'Java Developer', 0, TO_DATE('2019/01/13', 'yyyy/mm/dd'), 70000, 20000, 1)
    into employees values(4, 'Usamah', 'Java Developer', 0, TO_DATE('2019/01/14', 'yyyy/mm/dd'), 70000, 20000, 1)
    into employees values(5, 'Zaid', 'Java Developer', 0, TO_DATE('2019/01/15', 'yyyy/mm/dd'), 70000, 20000, 1)
    into employees values(6, 'Qomar', 'Senior Java Developer', 0, TO_DATE('2019/01/16', 'yyyy/mm/dd'), 80000, 20000, 1)
    into employees values(7, 'Sahin', 'Senior Java Developer', 0, TO_DATE('2019/01/17', 'yyyy/mm/dd'), 90000, 20000, 1)
    into employees values(8, 'Bakrin', 'Senior Java Developer', 0, TO_DATE('2019/01/18', 'yyyy/mm/dd'), 80000, 20000, 1)
    into employees values(9, 'Krstanto', 'Junior Java Developer', 0, TO_DATE('2019/01/19', 'yyyy/mm/dd'), 50000, 20000, 1)
    into employees values(10, 'Abdullah', 'Scrum Master', 0, TO_DATE('2019/01/20', 'yyyy/mm/dd'), 120000, 20000, 1)
  SELECT * FROM employees;
  /
  
  ALTER TABLE employees MODIFY job varchar2(150) not null;
  /
  
  ALTER TABLE employees MODIFY salary NUMBER(15,2);
  /
  
  select * from employees;
  /
  
  create table DEPARTMENTS (  
    deptno        number,  
    name          varchar2(50) not null,  
    location      varchar2(50),  
    constraint pk_departments primary key (deptno)  
  );
  /
  insert into departments values(1, 'IT Department', 'Jakarta');
  /