PROMPT Building demonstration tables for DESC utility.
PROMPT 

DROP VIEW dept_v;
DROP PACKAGE p_dept;
DROP TABLE emp;
DROP TABLE dept;

CREATE TABLE dept (
   deptno NUMBER(2) CONSTRAINT dept_pk PRIMARY KEY,
   dname VARCHAR2(14),
   loc VARCHAR2(13) 
);

CREATE TABLE emp (
	empno NUMBER(4),
        ename VARCHAR2(10) CONSTRAINT emp_nn_ename NOT NULL,
        job VARCHAR2(9),
        mgr NUMBER(4),
        hiredate DATE,
        sal NUMBER(7, 2),
        comm NUMBER(7, 2),
        deptno NUMBER(2),
   CONSTRAINT emp_pk PRIMARY KEY (empno),
   CONSTRAINT emp_uk UNIQUE (ename, hiredate), -- just for example
   CONSTRAINT check_sal CHECK (sal >= 0),
   CONSTRAINT emp_fk_dept FOREIGN KEY (deptno) REFERENCES dept (deptno)
);

CREATE INDEX i_emp_deptno ON emp (deptno);
CREATE INDEX i_emp_mgr ON emp (mgr);
CREATE INDEX i_emp_composite ON emp (job, mgr, ename);

COMMENT ON TABLE emp IS 'Сотрудники';
COMMENT ON COLUMN emp.empno IS 'Табельный номер';
COMMENT ON COLUMN emp.ename IS 'ФИО сотрудника';
COMMENT ON COLUMN emp.job IS 'Должность';
COMMENT ON COLUMN emp.mgr IS 'Табельный номер начальника';
COMMENT ON COLUMN emp.hiredate IS 'Дата приема на работу';
COMMENT ON COLUMN emp.sal IS 'Оклад';
COMMENT ON COLUMN emp.comm IS 'Премия';
COMMENT ON COLUMN emp.deptno IS 'Номер отдела';


CREATE OR REPLACE TRIGGER trg_emp
   BEFORE INSERT OR UPDATE OR DELETE 
   ON emp
BEGIN
   -- Some checks here
   NULL;
END;
/

CREATE OR REPLACE VIEW dept_v (
   dname, total_emps
) AS
SELECT d.dname, COUNT(e.deptno) AS total_emps
  FROM dept d, emp e
 WHERE d.deptno = e.deptno(+)
 GROUP BY d.dname
/

COMMENT ON TABLE dept_v IS 'Количество сотрудников в отделах';
COMMENT ON COLUMN dept_v.dname IS 'Название отдела';
COMMENT ON COLUMN dept_v.total_emps IS 'Количество сотрудников в отделе';

CREATE OR REPLACE PACKAGE p_dept
IS
   PROCEDURE ins (
      deptno_in dept.deptno%TYPE
     ,dname_in dept.dname%TYPE
     ,loc_in dept.loc%TYPE
   );
END p_dept;
/

CREATE OR REPLACE PACKAGE BODY p_dept
IS
   PROCEDURE ins (
      deptno_in dept.deptno%TYPE
     ,dname_in dept.dname%TYPE
     ,loc_in dept.loc%TYPE
   )
   IS
   BEGIN
      INSERT INTO dept (
         deptno, dname, loc
      ) VALUES (
         deptno_in, dname_in, loc_in
      );
   END ins;
END p_dept;
/

ALTER SESSION SET NLS_DATE_FORMAT='DD-MON-RR';
ALTER SESSION SET NLS_DATE_LANGUAGE='AMERICAN';

INSERT INTO DEPT VALUES (10, 'ACCOUNTING', 'NEW YORK');
INSERT INTO DEPT VALUES (20, 'RESEARCH',   'DALLAS');
INSERT INTO DEPT VALUES (30, 'SALES',      'CHICAGO');
INSERT INTO DEPT VALUES (40, 'OPERATIONS', 'BOSTON');

INSERT INTO EMP VALUES
        (7369, 'SMITH',  'CLERK',     7902,
        TO_DATE('17-DEC-1980', 'DD-MON-YYYY'),  800, NULL, 20);
INSERT INTO EMP VALUES
        (7499, 'ALLEN',  'SALESMAN',  7698,
        TO_DATE('20-FEB-1981', 'DD-MON-YYYY'), 1600,  300, 30);
INSERT INTO EMP VALUES
        (7521, 'WARD',   'SALESMAN',  7698,
        TO_DATE('22-FEB-1981', 'DD-MON-YYYY'), 1250,  500, 30);
INSERT INTO EMP VALUES
        (7566, 'JONES',  'MANAGER',   7839,
        TO_DATE('2-APR-1981', 'DD-MON-YYYY'),  2975, NULL, 20);
INSERT INTO EMP VALUES
        (7654, 'MARTIN', 'SALESMAN',  7698,
        TO_DATE('28-SEP-1981', 'DD-MON-YYYY'), 1250, 1400, 30);
INSERT INTO EMP VALUES
        (7698, 'BLAKE',  'MANAGER',   7839,
        TO_DATE('1-MAY-1981', 'DD-MON-YYYY'),  2850, NULL, 30);
INSERT INTO EMP VALUES
        (7782, 'CLARK',  'MANAGER',   7839,
        TO_DATE('9-JUN-1981', 'DD-MON-YYYY'),  2450, NULL, 10);
INSERT INTO EMP VALUES
        (7788, 'SCOTT',  'ANALYST',   7566,
        TO_DATE('09-DEC-1982', 'DD-MON-YYYY'), 3000, NULL, 20);
INSERT INTO EMP VALUES
        (7839, 'KING',   'PRESIDENT', NULL,
        TO_DATE('17-NOV-1981', 'DD-MON-YYYY'), 5000, NULL, 10);
INSERT INTO EMP VALUES
        (7844, 'TURNER', 'SALESMAN',  7698,
        TO_DATE('8-SEP-1981', 'DD-MON-YYYY'),  1500,    0, 30);
INSERT INTO EMP VALUES
        (7876, 'ADAMS',  'CLERK',     7788,
        TO_DATE('12-JAN-1983', 'DD-MON-YYYY'), 1100, NULL, 20);
INSERT INTO EMP VALUES
        (7900, 'JAMES',  'CLERK',     7698,
        TO_DATE('3-DEC-1981', 'DD-MON-YYYY'),   950, NULL, 30);
INSERT INTO EMP VALUES
        (7902, 'FORD',   'ANALYST',   7566,
        TO_DATE('3-DEC-1981', 'DD-MON-YYYY'),  3000, NULL, 20);
INSERT INTO EMP VALUES
        (7934, 'MILLER', 'CLERK',     7782,
        TO_DATE('23-JAN-1982', 'DD-MON-YYYY'), 1300, NULL, 10);



COMMIT;