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/* Do not edit this part ---------------------------------------------------*/
/* ------------------------------------------------------------------------ */
:- consult('emp.pl').
:- consult('subtotal.pl').
:- consult('query.pl').

%Database emp:
%emp(Empno, Ename, Job, Mgr, Hiredate, Sal, Comm, Deptno)
%dept(Deptno, Dname, Loc)
%salgrade(Grade, Losal, Hisal)

/* ------------------------------------------------------------------------ */
/* Example -----------------------------------------------------------------*/
/* ------------------------------------------------------------------------ */

/* Find the number of employees who work in Dallas. */

emp_dallas(E) :-
  emp(E, _, _, _, _, _, _, D),
  dept(D, _, dallas).

nr_emp_dallas(N) :-
  subtotal(emp_dallas(E), [], [N = count(E)]).

/* To run this query, use (in another window, after saving this file):
'pl -s queries_emp.pl'
and then (Prolog prompt):
make.
?- q(nr_emp_dallas(N)). 
*/

/* ------------------------------------------------------------------------ */
/* Write and test the following queries ----------------------------------- */
/* ------------------------------------------------------------------------ */

%Find average salary of employees who work in Dallas.

%For each department (including departments with no employees), find the sum of salaries of employees who work in that department.

%Find departments (deptno) with more than 3 employees.

%For each department, find the number of analysts who work in that department (the result consists of tuples [D, N]).

%Find the job position(s) with the maximal standard deviation of salaries.

%Find tuples [Deptno, Job, Sum, Average] which for each [Deptno, Job] state the sum of salaries and average salary of employees who work in department Deptno and do job Job.

%Datalog only: For each employee, find the number of subsidiaries (direct and indirect) of that employee. Include employees with no subsidiaries.