Drools exercises solutions

Basic

Ex1

 rule "Exercise 1 Select all Salgrade facts"
 when 
 
   $s : Salgrade()
 then    
   System.out.println($s.grade + '\t' + $s.losal + '\t' + $s.hisal)
 end

Ex2

 //Select shown data about employees who earn between 1000 and 2000.
 rule "Ex-2"
 when
 	$e : Emp(sal > 1000, sal < 2000)
 then
 	System.out.println($e.id + " " + $e.sal );
 end

Ex3

 // Select clerks working in department no 20.
  rule "showclerkofdeptno20" enabled true
 when 
  $e: Emp(job == "CLERK" && deptno == 20) 
 then    
  System.out.println($e.id + " " + $e.name + " " + $e.job + " " + $e.mgr + " " + $e.hiredate + " " + $e.sal + " " + $e.deptno)
  end

Ex4

 rule "Sample3" enabled false
 when 
      $e:Emp(mgr!=0)
 then    
  System.out.println($e.id + " " + $e.name + "\t" + $e.deptno+ "\t" + $e.sal )
 end

Ex4 ver 2

rule "Ex4"
when 
	$e: Emp($mgr :mgr)
	not Emp(id == $mgr)
	//not (exists Emp(id == $mgr))
then    
  System.out.println($e.name)
end

EX5

  rule "showmgrannualrem"
 when
  $e: Emp(job == "MANAGER") 
 then   
  System.out.println($e.id + " " + $e.name + " " + $e.job + " " + $e.mgr + " " + $e.hiredate + " " + $e.sal*12 + " " + $e.deptno)
  end

EX5 ver 2

  rule "showmgrannualrem"
when 
 $e : Emp( job == "MANAGER",$sal : sal )
then    
  System.out.println($e.name + " " + $sal * 12 )
end

EX6

 // Find employees with second letter L and third A
 rule "EX6" enabled false
 when
	$e: Emp(name matches '.LA.*')
 then
	System.out.println($e.name);
 end

EX7

  rule "Find employees whose name contains T and ends with N" 
  when
  $e:Emp(name matches ".*T.*N")
    then
   System.out.println(" matches L.*$N")
   System.out.println($e.id+"  "+$e.name+"   "+$e.job+"  "+$e.sal)
   end

Ex8

 // Find employees who either work as managers or work in department no 10, but not both.
 rule "Ex_08"
 
     when
         $e : Emp ((deptno == '10' || $e.job == 'MANAGER')  && !(deptno == '10' &&  $e.job == 'MANAGER'))
         //$e : Emp( (job == "MANAGER" && deptno != 10) || ( deptno == "10" && job not in ("MANAGER")  ) )
     then
        System.out.println("Ex_08-" + $e.name + "job-" + $e.job +" salgrade="+ $e.deptno) ;
  
 end

Ex8 version 2

 rule "Find employees who either work as managers or work in department no 10, but not both" enabled true
 when
    $e: Emp((job == 'MANAGER' && deptno != 10) || (deptno == 10 && job != 'MANAGER'))
 then
    System.out.println($e.name + " " + $e.job + " " + $e.deptno);
 end

Advanced

Ex23

  rule "excersie23"
 when 
 accumulate(e:Emp(hiredate==1981),$avg : average(e.sal),$minsal:min(e.sal),$maxsal:max(e.sal))
 then 
 System.out.println(   "Average salary  " +$avg +"Min salary  " +$minsal+"max salary  " +$maxsal )   
 end

Ex24

 // Find the difference between maximal and minimal salary
 rule "EXE 24" enabled true
 when
  accumulate ($e :Emp(), $min : min($e.sal), $max : max($e.sal)) 
 then    
  System.out.println("Difference between maximal and minimal salary: " + ($max - $min) + "\n");
 end

Ex25

 // Find the average salary for every post.

 declare SalByJob1
   job : String
   //avgSal : Double
 end

 rule "EXE 25" enabled true
 when
   Emp($j: job) and
   not SalByJob1($j == job)
   accumulate ($e :Emp(job == $j), 	$avg : average($e.sal)   	) 
 then    
	
   System.out.println(    $j + " " + $avg + "\n");
   //insert(new SalByJob($j,$avg))
   insert(new SalByJob1($j))
 end

Ex26

 // How many managers work for the company?

 rule "EXE 26" enabled true
 when
  accumulate ($e :Emp(job == 'MANAGER'), $cnt : count($e.job)) 
 then    
  System.out.println("How many managers work for the company: " + $cnt + "\n");
 end

Ex27

declare SalByDept
  deptno : Integer
end

rule "EX 27 Find the average annual salaries in departments" enabled false
when
 Emp(d: deptno) and  
 not SalByDept(d == deptno)
 accumulate (e :Emp(deptno == d), $avg : average(e.sal*12)) 
then    
  System.out.println("Salaries in dept " + d + " " + $avg)
   insert(new SalByDept(d))
end

Ex28

declare EmpByDept
  deptno : Integer
end

rule "EX 28 Find departments with more than 3 workers."
when
 Emp(d: deptno) and  
 not EmpByDept(d == deptno)
 accumulate (e :Emp(deptno == d), cn : count(e.id)) 
 Number(intValue > 3) from cn
then    
  System.out.println("Employees in dept " + d + ": " + cn)
   insert(new EmpByDept(d))
end

Exe31

 rule "EmployeeLocation31" enabled false
 when
   d :Dept()
   e :Emp(d.deptno == deptno)
 then    
  System.out.println(e.name + "\t" + d.loc)
 end

Exe32

 rule "Ex_32"
 when
 	e : Emp()
 	d : Dept(  e.deptno == deptno);
 then
 	System.out.println("----------------------");    
     System.out.println(
        e.name + "	\t" +  d.dname + " \t" + e.deptno);
 end

Exe33

 rule "salarygrade33" enabled false
 when
   s :Salgrade()
   e :Emp(e.sal>=2000,e.sal>=s.losal,e.sal<=s.hisal)
 then    
  System.out.println(e.name + "\t" + e.sal+"\t"+s.grade)
 end

Exe33 ver 2

 rule "salarygrade33" enabled false
 when
   e :Emp(sal>=2000)
   s :Salgrade(e.sal>=losal,e.sal<=hisal)
 then    
  System.out.println(e.name + "\t" + e.sal+"\t"+s.grade)
 end

Exe34

 rule "workingLondon34" enabled false
 when
   d :Dept(loc=='LONDON')
   e :Emp(d.deptno == deptno)
 then    
  System.out.println(e.name + "\t" + d.loc);
 end

Exe35

 rule "Ex-35" 
 when
    $e : Emp()
    $d : Dept(deptno == $e.deptno, loc != 'LONDON')
    $s : Salgrade($e.sal > losal, $e.sal < hisal)
 then
    System.out.println($e.name+"  "+$d.loc+"  "+$s.grade );
 end

Exe36

rule "36 Exercise"	
    enabled false
when
  d:Dept()
  not (Emp(deptno == d.deptno))
then    
  System.out.println( d.dname )

   end

Exe37

   
    rule "37 Exercise"	
     enabled false
when
  d:Emp()
  e:Emp(d.id==e.mgr)
then    
  System.out.println(   e.name +"boss is   "+ d.name);

   end

Exe39

    
   rule "39 Exercise"	
when
  d:Emp()
 not (Emp(d.id==mgr))
then    
  System.out.println(    d.name);

   end

Exe41

  
rule "Ex-41" 
when
	$e1 : Emp()
	$e2 : Emp(id == $e1.mgr, hiredate > $e1.hiredate)
then
	System.out.println( $e1.name+"  "+ $e2.name);
end

Exe43

   
declare FilledJobs
   job : String   
end
rule "Exercise43"
when
   e :Emp(e.hiredate in(1982 ,1983 )) && not FilledJobs(e.job == job)
then    
  System.out.println(e.job)
  insert(new FilledJobs(e.job))
end

Exe44

   

rule "Exercise44"
when
   e :Emp(e.deptno ==10)
 not (Emp (e.job == job && deptno ==20))
then    
  System.out.println(e.job)
end

Exe45

   
rule "Ex 45 Find employees earning more than the manager’s (job=='MANAGER') average." enabled true
when
  Number($avg :longValue  ) from accumulate (Emp(s: sal, job == "MANAGER"), average(s))
  e : Emp(sal > $avg)
then    
  System.out.println(e.name + " " + e.sal)
end

Exe46

Solution 1

   
declare xJob
   name : String
end

rule "Ex 46 Find Select employees earning the maximum salaries in their positions (jobs)." enabled true
//doesn't work if two people earn max values (TOOSK and CARNEGIE - both at analys positions)

when
	Emp($j :job) and not(xJob(name == $j))
	Number($max :longValue) from accumulate (Emp(s: sal,job == $j ), max(s))
	e : Emp(job == $j,sal == $max)
then    
  System.out.println(e.name + "\t" + e.deptno + "\t" + e.sal)
  insert(new xJob($j));
end

Solution 2

declare jobPost2
	job: String
	max: Double
end

rule "Exercise 46" 

when 
	Emp(j:job)
	and not jobPost2(j == job)
	Number(max:doubleValue) from accumulate(Emp(s:sal, job==j), max(s)) 
then
	insert(new jobPost2(j, max))
end 

rule "Display"

when
	jp: jobPost2(j: job, m: max)
	e: Emp (e.sal == m, e.job == j)
then
	System.out.println(e.name + " " + e.sal)
end

Exe51

   
rule "Ex 51 Find employees earning more than the average salary in their department."
when
	Dept(dn :deptno)
	Number($avg :longValue) from accumulate (Emp(s: sal,deptno == dn ), average(s))
	e : Emp(deptno == dn,sal > $avg)
then    
  System.out.println(e.name + "\t" + e.deptno + "\t" + e.sal)
end

Exe55

 
rule "Ex 55" enabled true
when
  $d: Dept(dn :deptno)
  Number($avg :longValue  ) from accumulate (Emp(s: sal,deptno == dn ), average(s))
then    
  insert (new DepsAvg($d, $avg))
  //System.out.println(($maxAvg))
end

rule "Ex 55 second step" enabled true
when
  Number($max :longValue  )  from accumulate ($da :DepsAvg() , max($da.depAverage))
then      
  System.out.println($max)
end