Conceptual Data Model Conceptual Data Model

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					Conceptual Data Model


         Principles
     Graphical Languages
          Modeling
         Constraints




    Bogdan Shishedjiev Conceptual Data   1
                 Model
                           Principles
• Main approach – object-oriented
   –   Class (entity set, object)
   –   Association (relationship, relation)
   –   Data member (attribute, property)
   –   Instance (entity, occurrence)




                   Bogdan Shishedjiev Conceptual Data Model   2
                           Languages
• Entity Relationship model (E-R) (ERM)
   – Entity set
   – Relationship
   – Attribute




                    Bogdan Shishedjiev Conceptual Data Model   3
                         Languages
• MERISE
  – Object with occurrences
  – Relation
  – Propertiy



                               ENROLL



  STUDENT                                                        SUBJECT
                                                             -Name
-Name
-Address                     IS GIVEN
                            TEXTBOOK



                  Bogdan Shishedjiev Conceptual Data Model                 4
                    Languages
• Object Role Modeling (ORM)




             Bogdan Shishedjiev Conceptual Data Model   5
                          Languages
 • Class Diagram
    – Class with instances
    – Association
    – Property


 STUDENT
              +enrolls     +is enrolled          SUBJECT
+Name
+FamilyName                                    +SubName
+Address      *                          *




                   Bogdan Shishedjiev Conceptual Data Model   6
                        Conceptual Model
   • Goals
       – Starting from the dictionary and the rules this model tries to reveal
         the relations among the data and their interaction
   • Example – School
Rules                                         Dictionary
1. Every class has a one and only             • Student’s Address,
   one room.                                  • Subject,
2. Every subject is teaches by only           • Number of Hours,
   one teacher.                               • Class Name,
3. Every class is taught a subject a          • Student's Family Name,
   fixed number of hours.                     • Teacher‘s Name,
4. Every student can have no more             • Mark,
   one mark in every subject.                 • Room Number,
5. The school manages the                     • Student’s Name
   timetable and the rating of
   students and teachers..

                         Bogdan Shishedjiev Conceptual Data Model                7
                           Concepts
• Class (Entity class, Entity instance)
• Association
   – Relationship between entity instances
• Attribute
   – Properties




                  Bogdan Shishedjiev Conceptual Data Model   8
                  Defining an Entity Class
• Give it a name (a noun)
• Define its attributes
• Define the rules
   – What belongs to the class?
   – How the instances are identified in the class?
• Identifying an instance (Identifier)

         NAME                                       STUDENT
                                                1.First Name
    1.Attribute                                 2.Last Name
    2.Attribute                                 3.Address


                     Bogdan Shishedjiev Conceptual Data Model   9
                        Association
• Give a name (a verb)
• Determine the
  participating classes
• Define the cardinalities




                  Bogdan Shishedjiev Conceptual Data Model   10
        Examples




Bogdan Shishedjiev Conceptual Data Model   11
Identifier of an Association




    Bogdan Shishedjiev Conceptual Data Model   12
          Cardinalities of an Association
•   Cardinalities One to One
    –   0..1 – 0..1 – Every student
        can use one locker



    –   0..1 – 1




    –   1 – 1 Every student uses
        a locker and ther are no
        free lockers




                     Bogdan Shishedjiev Conceptual Data Model   13
         Cardinalities of an Association
• Cardinalities One to Many
   – 1 – 1..N




   – 0..1 – 1..N




   – 1 – 0..N



   – 0..1 – 0..N

                   Bogdan Shishedjiev Conceptual Data Model   14
         Cardinalities of an Association
• Cardinalities Many to
  Many
   – 1..N – 1..N




   – 0..N – 1..N




   – 0..N – 0..N




                   Bogdan Shishedjiev Conceptual Data Model   15
           Cardinalities of an Association
•   Generalization
    – Minimal cardinality
       •    Mandatory participation of every instance - 1
       •    Optionally participation of every instance - 0
    – Maximal cardinality
       •    To only one instance of the other class – 1
       •    To multiple instances of the other class - N




                    Bogdan Shishedjiev Conceptual Data Model   16
            Dimension of an Association
• Number of different classes participating in it
• Multidimensional

                            Make cours
                           -HourNumber




                  -End4                        -End3
    TEACHER         *                            *      SUBJECT
   -TeacherName                                        -SubName
                                   -End5
                                      *




                               ROOM
                           -RoomNo




                          Bogdan Shishedjiev Conceptual Data Model   17
         Dimension of an Association
•   Multidimensional




                Bogdan Shishedjiev Conceptual Data Model   18
         Dimension of an Association
•   One-dimensional
    (Reflexive)




                Bogdan Shishedjiev Conceptual Data Model   19
            Aggregate Associations
• Aggregation




• Composition




                Bogdan Shishedjiev Conceptual Data Model   20
                       Weak Entities
• It is identified through the association




                   Bogdan Shishedjiev Conceptual Data Model   21
                 Recommendations
• Don’t use high dimension associations
• Be aware not replace classes by associations




                 Bogdan Shishedjiev Conceptual Data Model   22
          Case Study – Management Rules
1.   A patient is characterized by:             6. Each specialist has one or more
     –   Unique Number                              specialties
     –   Name                                   7. Each specialist can give consultations
     –   address                                    in one or more policlinics
     –   Phone Number                           8. Each policlinic groups several
2.   General practitioner is characterized          specialists
     by:                                        9. A patient can make an appointment for
     –   Serial Number                              a consultation with specialist in a given
     –   Name                                       policlinic, The specialist must work in
     –   Phone Number                               this policlinic
3.   Each patient is supervised by a GP         10. The appointment is for a date that is
4.   A policlinic is characterized by:              later than the date of appointment
     –   Name                                   11. If the consultation does not take place a
     –   Address                                    new appointment must be made no
     –   Phone Number
                                                    matter what are reasons for the failure
5.   A specialist is characterized by:          12. Lists of appointment for every
                                                    specialist are made at the beginning of
     –   Serial Number                              the day.
     –   Name
     –   Phone Number
                                                13. In the end of every day two reports are
                                                    made:
                                                      –   A log of appointment made
                                                      –   A log of consultations done



                           Bogdan Shishedjiev Conceptual Data Model                        23
Case Study - Policlinic




  Bogdan Shishedjiev Conceptual Data Model   24
Case Study - Policlinic




  Bogdan Shishedjiev Conceptual Data Model   25
                        Subtypes
• Example – Hardware
  components order




               Bogdan Shishedjiev Conceptual Data Model   26
         Subtypes




Bogdan Shishedjiev Conceptual Data Model   27

				
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posted:4/14/2012
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