Cartesian Products

CREATE TABLE departments
(department_id             number(10)            not null,
 department_name           varchar2(50)      not null,
 CONSTRAINT departments_pk PRIMARY KEY (department_id)
);

insert into departments ( department_id, department_name )values(1,'Data Group' );
insert into departments ( department_id, department_name )values(2,'Purchasing' );
insert into departments ( department_id, department_name )values(3,'Call Center' );
insert into departments ( department_id, department_name )values(4,'Communication' );

CREATE TABLE employees
( employee_id          number(10)      not null,
  last_name            varchar2(50)      not null,
  job_id               varchar2(30),
  department_id        number(10),
  salary               number(6),
  manager_id           number(6),
  CONSTRAINT           employees_pk PRIMARY KEY (employee_id),
  CONSTRAINT           fk_departments FOREIGN KEY (department_id) 
                       REFERENCES departments(department_id)
);
insert into employees( employee_id, last_name, job_id, salary,department_id ,manager_id)
values(                1001,        'Lawson',  'MGR',  30000, 1,             1004);
insert into employees( employee_id, last_name, job_id, salary, department_id ,manager_id)
values(                1002,        'Wells',   'DBA',  20000, 2,             1005 );
insert into employees( employee_id, last_name, job_id, salary, department_id ,manager_id)
values(                1003,        'Bliss',   'PROG', 24000, 3,             1004);
insert into employees( employee_id, last_name, job_id, salary, department_id, manager_id)
values(                1004,        'Kyte',    'MGR',  25000 ,4,             1005);
insert into employees( employee_id, last_name, job_id, salary, department_id, manager_id)
values(                1005,        'Viper',   'PROG', 20000, 1,             1006);
insert into employees( employee_id, last_name, job_id, salary, department_id,manager_id)
values(                1006,        'Beck',    'PROG', 20000, 2,             null);
insert into employees( employee_id, last_name, job_id, salary, department_id, manager_id)
values(                1007,        'Java',    'PROG', 20000, 3,             1006);
insert into employees( employee_id, last_name, job_id, salary, department_id, manager_id)
values(                1008,        'Oracle',  'DBA',  20000, 4,             1006);

SQL> select employee_id, last_name, department_name
  2  from employees, departments;

EMPLOYEE_ID LAST_NAME    DEPARTMENT_NAME
----------- --------------------------------------------------
       1001 Lawson       Data Group
       1002 Wells        Data Group
       1003 Bliss        Data Group
       1004 Kyte         Data Group
       1005 Viper        Data Group
       1006 Beck         Data Group
       1007 Java         Data Group
       1008 Oracle       Data Group
       1001 Lawson       Purchasing
       1002 Wells        Purchasing
       1003 Bliss        Purchasing
       1004 Kyte         Purchasing
       1005 Viper        Purchasing
       1006 Beck         Purchasing
       1007 Java         Purchasing
       1008 Oracle       Purchasing
       1001 Lawson       Call Center
       1002 Wells        Call Center
       1003 Bliss        Call Center
       1004 Kyte         Call Center
       1005 Viper        Call Center
       1006 Beck         Call Center
       1007 Java         Call Center
       1008 Oracle       Call Center
       1001 Lawson       Communication
       1002 Wells        Communication
       1003 Bliss        Communication
       1004 Kyte         Communication
       1005 Viper        Communication
       1006 Beck         Communication
       1007 Java         Communication
       1008 Oracle       Communication
32 rows selected.

SQL>