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{{Cat|Drools Filip|050}}

== Drools Expert - mvel - RHS - basic Training Materials ==
{{Can I use your material}}

== Overview ⌘==

'''Facts used during course'''

'''Emp'''

+------+----------+-----------+------+----------+---------+--------+
| id | name | job | mgr | hiredate | sal | deptno |
+------+----------+-----------+------+----------+---------+--------+
| 7839 | BUSH | PRESIDENT | 0 | 1981 | 5000.00 | 10 |
| 7698 | BLAIR | MANAGER | 7839 | 1981 | 2850.00 | 30 |
| 7782 | MERKEL | MANAGER | 7839 | 1981 | 2450.00 | 10 |
| 7566 | PUTIN | MANAGER | 7839 | 1981 | 2975.00 | 20 |
| 7654 | CHIRACK | SALESMAN | 7698 | 1981 | 1250.00 | 30 |
| 7499 | BAROSSO | SALESMAN | 7698 | 1981 | 1600.00 | 30 |
| 7844 | GATES | SALESMAN | 7698 | 1981 | 1500.00 | 30 |
| 7900 | BUFFETT | CLERK | 7698 | 1981 | 950.00 | 30 |
| 7521 | WALTON | SALESMAN | 7698 | 1981 | 1250.00 | 30 |
| 7902 | TOOSK | ANALYST | 7566 | 1981 | 3000.00 | 20 |
| 7369 | THATCHER | CLERK | 7902 | 1980 | 800.00 | 20 |
| 7788 | CARNEGIE | ANALYST | 7566 | 1982 | 3000.00 | 20 |
| 7876 | FORD | CLERK | 7788 | 1983 | 1100.00 | 20 |
| 7934 | ELISON | CLERK | 7782 | 1982 | 1300.00 | 10 |
+------+----------+-----------+------+----------+---------+--------+

'''Dept'''
+--------+------------+----------+
| deptno | dname | loc |
+--------+------------+----------+
| 10 | ACCOUNTING | NEW YORK |
| 20 | RESEARCH | LONDON |
| 30 | SALES | PARIS |
| 40 | OPERATIONS | BERLIN |
+--------+------------+----------+

'''Salgrade'''
+-------+-------+-------+
| grade | losal | hisal |
+-------+-------+-------+
| 1 | 700 | 1200 |
| 2 | 1201 | 1400 |
| 3 | 1401 | 2000 |
| 4 | 2001 | 3000 |
| 5 | 3001 | 9999 |
+-------+-------+-------+

=== Comments ⌘===
Use double forward slash to comment a whole line

// This is commented line

Use C langue comment notation (/* and */) to comment some text inside a line or a couple of lines.

So please comment your answer to exercises, for example
/**
* Exercise 4
*/
when
e : Emp()
then
....

== Filtering ==

=== Filter by Fact Type ⌘===
Find all facts of ''Emp'' type
when
e : Emp()
then
System.out.println(
e.id + " " +
e.name + "\t" +
e.job + " \t" +
e.mgr + "\t" +
e.hiredate + " " +
e.sal + " " +
e.deptno );
end

7934 ELISON CLERK 7782 1982 1300 10
7876 FORD CLERK 7788 1983 1100 20
7788 CARNEGIE ANALYST 7566 1982 3000 20
7369 THATCHER CLERK 7902 1980 800 20
7902 TOOSK ANALYST 7566 1981 3000 20
7521 WALTON SALESMAN 7698 1981 1250 30
7900 BUFFETT CLERK 7698 1981 950 30
7844 GATES SALESMAN 7698 1981 1500 30
7499 BAROSSO SALESMAN 7698 1981 1600 30
7654 CHIRACK SALESMAN 7698 1981 1250 30
7566 PUTIN MANAGER 7839 1981 2975 20
7782 MERKEL MANAGER 7839 1981 2450 10
7698 BLAIR MANAGER 7839 1981 2850 30
7839 BUSH PRESIDENT 0 1981 5000 10

=== Filtering by field ⌘===

Filter employees earning more than 1500.
when
e : Emp(sal > 1500)
then
System.out.println(e.id + " " + e.name + "\t" + e.job
+ " \t" + e.mgr + "\t" + e.hiredate + " " + e.sal
+ " " + e.deptno );
end

7788 CARNEGIE ANALYST 7566 1982 3000 20
7902 TOOSK ANALYST 7566 1981 3000 20
7499 BAROSSO SALESMAN 7698 1981 1600 30
7566 PUTIN MANAGER 7839 1981 2975 20
7782 MERKEL MANAGER 7839 1981 2450 10
7698 BLAIR MANAGER 7839 1981 2850 30
7839 BUSH PRESIDENT 0 1981 5000 10

=== Operators ⌘===
There are different kinds of operators:
* Arithmetic operators (+, -, *, /, %, MOD, DIV)
* Relational operators (>, >=, ==, !=)
* Logical operators
** conjunction (and, &&, ",")
** disjunction (or, ||)
** negation (!, do not confuse with ''not'')
* Drools operators (in, matches, etc...)

==== Relational operators ⌘====

Find managers
rule "Sample"
when
e : Emp(job == "MANAGER")

7566 PUTIN MANAGER 7839 1981 2975 20
7782 MERKEL MANAGER 7839 1981 2450 10
7698 BLAIR MANAGER 7839 1981 2850 30

People hired in 1982
when
e : Emp(hiredate == 1982)

7934 ELISON CLERK 7782 1982 1300 10
7788 CARNEGIE ANALYST 7566 1982 3000 20

Select all except clerks.
when
e : Emp(job != 'CLERK')

7788 CARNEGIE ANALYST 7566 1982 3000 20
7902 TOOSK ANALYST 7566 1981 3000 20
7521 WALTON SALESMAN 7698 1981 1250 30
7844 GATES SALESMAN 7698 1981 1500 30
7499 BAROSSO SALESMAN 7698 1981 1600 30
7654 CHIRACK SALESMAN 7698 1981 1250 30
7566 PUTIN MANAGER 7839 1981 2975 20
7782 MERKEL MANAGER 7839 1981 2450 10
7698 BLAIR MANAGER 7839 1981 2850 30
7839 BUSH PRESIDENT 0 1981 5000 10

To select people earning from 1000 to 2000 (inclusive)

when
e : Emp(sal >= 1000 , sal <= 2000)

7934 ELISON CLERK 7782 1982 1300 10
7876 FORD CLERK 7788 1983 1100 20
7521 WALTON SALESMAN 7698 1981 1250 30
7844 GATES SALESMAN 7698 1981 1500 30
7499 BAROSSO SALESMAN 7698 1981 1600 30
7654 CHIRACK SALESMAN 7698 1981 1250 30

All lines below are equivalent
e : Emp(sal >= 1000 , sal <= 2000)
e : Emp(sal >= 1000 && sal <= 2000)
e : Emp(sal >= 1000 && <= 2000)

==== ''in'' operator ⌘====

The ''in'' operator checks if the value is in a set.

Select people working in department no 10 or 20.

when
e : Emp(deptno in (10,20))

7934 ELISON CLERK 7782 1982 1300 10
7876 FORD CLERK 7788 1983 1100 20
7788 CARNEGIE ANALYST 7566 1982 3000 20
7369 THATCHER CLERK 7902 1980 800 20
7902 TOOSK ANALYST 7566 1981 3000 20
7566 PUTIN MANAGER 7839 1981 2975 20
7782 MERKEL MANAGER 7839 1981 2450 10
7839 BUSH PRESIDENT 0 1981 5000 10

The above is equivalent to
e : Emp(deptno == 10 || deptno == 20)
e : (Emp(deptno == 10) or Emp(deptno == 20))

The above two lines are assessed by the Drools engine in completely different way.
The ''or'' keywords will split the rule in two separate rules.
PLEASE SEE RETE TREE FOR THOSE EXAMPLES!

Select managers or clerks.

when
e : Emp(job in ('CLERK','MANAGER'))

7934 ELISON CLERK 7782 1982 1300 10
7876 FORD CLERK 7788 1983 1100 20
7369 THATCHER CLERK 7902 1980 800 20
7900 BUFFETT CLERK 7698 1981 950 30
7566 PUTIN MANAGER 7839 1981 2975 20
7782 MERKEL MANAGER 7839 1981 2450 10
7698 BLAIR MANAGER 7839 1981 2850 30

==== ''matches'' operator ⌘====

The 'maches' operator checks whether the values match the pattern (java regular expression).

'''.*''' matches any number of characters, even an empty string.
'''.''' matches exactly one character
More information:
http://docs.oracle.com/javase/6/docs/api/java/util/regex/Pattern.html

Select people with names starting with "B".

when
e: Emp(name matches "B.*")

7900 BUFFETT CLERK 7698 1981 950 30
7499 BAROSSO SALESMAN 7698 1981 1600 30
7698 BLAIR MANAGER 7839 1981 2850 30
7839 BUSH PRESIDENT 0 1981 5000 10

Select people with second letter ‘a’.

when
e: Emp(name matches ".A.*")

7788 CARNEGIE ANALYST 7566 1982 3000 20
7521 WALTON SALESMAN 7698 1981 1250 30
7844 GATES SALESMAN 7698 1981 1500 30
7499 BAROSSO SALESMAN 7698 1981 1600 30

==== ''not matches'' operator ⌘====
when
e: Emp(name not matches "B.*")

Note that this syntax is incorrect
when
e: Emp(name ! matches "B.*")

e: ! Emp(name matches "B.*")

==== Compound conditions ⌘====

You may use logical operators to build compound conditions.

* "and", "&&", "," (conjunction)
* "or", "||" (disjunction)
* "not", "!" (negation)

'''Examples'''

Let’s find managers earning more than 2500.

when
e: Emp(job == "MANAGER" , sal > 2500)

7566 PUTIN MANAGER 7839 1981 2975 20
7698 BLAIR MANAGER 7839 1981 2850 30

The line below gives the same result
when
e: Emp(job == "MANAGER" && sal > 2500)
Not that the "," and "&&" have different priority

=== Operators priority ⌘===

(nested) property access .
List/Map access [ ]
constraint binding :
multiplicative * / %
additive + -
shift << >> >>>
relational < > <= >= instanceof
equality == !=
bit-wise non-short circuiting AND &
bit-wise non-short circuiting exclusive OR ^
bit-wise non-short circuiting inclusive OR |
logical AND &&
logical OR ||
ternary ? :
Comma separated AND ,

==Exercises ==
'''1. Exercise'''

Select all Salgrade facts

5 3001 9999
4 2001 3000
3 1401 2000
2 1201 1400
1 700 1200

'''2. Exercise'''

Select shown data about employees who earn between 1000 and 2000.

7934 ELISON CLERK 7782 1982 1300 10
7876 FORD CLERK 7788 1983 1100 20
7521 WALTON SALESMAN 7698 1981 1250 30
7844 GATES SALESMAN 7698 1981 1500 30
7499 BAROSSO SALESMAN 7698 1981 1600 30
7654 CHIRACK SALESMAN 7698 1981 1250 30

'''3. Exercise'''

Select clerks working in department no 20.

7876 FORD CLERK 7788 1983 1100 20
7369 THATCHER CLERK 7902 1980 800 20

'''4. Exercise'''

Select employees who have a boss.

7934 ELISON CLERK 7782 1982 1300 10
7876 FORD CLERK 7788 1983 1100 20
7788 CARNEGIE ANALYST 7566 1982 3000 20
7369 THATCHER CLERK 7902 1980 800 20
7902 TOOSK ANALYST 7566 1981 3000 20
7521 WALTON SALESMAN 7698 1981 1250 30
7900 BUFFETT CLERK 7698 1981 950 30
7844 GATES SALESMAN 7698 1981 1500 30
7499 BAROSSO SALESMAN 7698 1981 1600 30
7654 CHIRACK SALESMAN 7698 1981 1250 30
7566 PUTIN MANAGER 7839 1981 2975 20
7782 MERKEL MANAGER 7839 1981 2450 10
7698 BLAIR MANAGER 7839 1981 2850 30

'''5. Exercise'''

Select manager’s annual remuneration.

7566 PUTIN MANAGER 7839 1981 35700 20
7782 MERKEL MANAGER 7839 1981 29400 10
7698 BLAIR MANAGER 7839 1981 34200 30

'''6. Exercise'''

Find employees with second letter “L” and third “A”.

BLAIR

'''7. Exercise'''
Find employees whose name ends with N and contains T.

PUTIN
WALTON

'''8. Exercise'''

Find employees who either work as managers or work in department no 10, but not both.

BUSH PRESIDENT 10
BLAIR MANAGER 30
PUTIN MANAGER 20
ELISON CLERK 10

MVEL basic - Revision history

Fstachecki: /* Comments ⌘ */