--drop table emp;
--drop table dept;
--drop function low_high_salaries;

create table dept(  
  deptno     integer,  
  dname      varchar(20),  
  loc        varchar(20),
  constraint pk_dept primary key (deptno) 
);

create table emp(  
  empno    integer,  
  ename    varchar(10),  
  job      varchar(9),  
  mgr      integer,  
  hiredate date,  
  sal      integer,  
  comm     integer,  
  deptno   integer,  
  constraint pk_emp primary key (empno),  
  constraint fk_deptno foreign key (deptno) references dept (deptno)  
);

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')
;
commit;

insert into emp  
values(  
 7839, 'KING', 'PRESIDENT', null,  
 to_date('17-11-1981','dd-mm-yyyy'),  
 5000, null, 10  
);
insert into emp  
values(  
 7698, 'BLAKE', 'MANAGER', 7839,  
 to_date('1-5-1981','dd-mm-yyyy'),  
 2850, null, 30  
);
insert into emp  
values(  
 7782, 'CLARK', 'MANAGER', 7839,  
 to_date('9-6-1981','dd-mm-yyyy'),  
 2450, null, 10  
);
insert into emp  
values(  
 7566, 'JONES', 'MANAGER', 7839,  
 to_date('2-4-1981','dd-mm-yyyy'),  
 2975, null, 20  
);
insert into emp  
values(  
 7788, 'SCOTT', 'ANALYST', 7566,  
 to_date('13-7-87','dd-mm-rr'),  
 3000, null, 20  
);
insert into emp  
values(  
 7902, 'FORD', 'ANALYST', 7566,  
 to_date('3-12-1981','dd-mm-yyyy'),  
 3000, null, 20  
);
insert into emp  
values(  
 7369, 'SMITH', 'CLERK', 7902,  
 to_date('17-12-1980','dd-mm-yyyy'),  
 800, null, 20  
);
insert into emp  
values(  
 7499, 'ALLEN', 'SALESMAN', 7698,  
 to_date('20-2-1981','dd-mm-yyyy'),  
 1600, 300, 30  
);
insert into emp  
values(  
 7521, 'WARD', 'SALESMAN', 7698,  
 to_date('22-2-1981','dd-mm-yyyy'),  
 1250, 500, 30  
);
insert into emp  
values(  
 7654, 'MARTIN', 'SALESMAN', 7698,  
 to_date('28-9-1981','dd-mm-yyyy'),  
 1250, 1400, 30  
);
insert into emp  
values(  
 7844, 'TURNER', 'SALESMAN', 7698,  
 to_date('8-9-1981','dd-mm-yyyy'),  
 1500, 0, 30  
);
insert into emp  
values(  
 7876, 'ADAMS', 'CLERK', 7788,  
 to_date('13-7-87', 'dd-mm-rr') - 51,  
 1100, null, 20  
);
insert into emp  
values(  
 7900, 'JAMES', 'CLERK', 7698,  
 to_date('3-12-1981','dd-mm-yyyy'),  
 950, null, 30  
);
insert into emp  
values(  
 7934, 'MILLER', 'CLERK', 7782,  
 to_date('23-1-1982','dd-mm-yyyy'),  
 1300, null, 10  
);
commit;


CREATE OR REPLACE FUNCTION low_high_salaries (dpet_id integer)
  RETURNS TABLE(low_sal INTEGER, high_sal INTEGER) AS
$$
BEGIN
 RETURN QUERY
 
   select min(sal) as minsal, max(sal) as maxsal
   from emp
   where deptno = dpet_id;
 
END; $$
LANGUAGE plpgsql;

SELECT * FROM emp;
SELECT * FROM dept;
select * from low_high_salaries(20);