Presentation database about ERD

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  • 1. GROUP MEMBERS NO. MATRIX GROUP ELIS ERVINA BINTI SULIMAN 2012967249 CS 241 3B ERLIA NADIA BINTI AB. MALEK 2012996329 CS 241 3B NORA SYAMIMI BINTI KHAIRUDDIN 2012949807 CS 241 3B NORHIDAYAH BINTI ZULKEFLI 2012755781 CS224 3A
  • 2. CAR MOD_CODE CAR_VIN CAR_COLOR CAR_YEAR CHEN MODEL CAR PK CAR_VIN MOD_CODE CAR_YEAR CAR_COLOR CROW’S FOOT MODEL
  • 3. BASIC SYMBOLS
  • 4. TERMINOLOGY Entity type a collections of things, represent collection of physical things such as person, places, event, or things. Attributes A property of an entity type or relationship. Each attributes has a data type that defines the kind of values and permission operation on the attributes. Relationship association among entity types, usually two-way or bidirectional. In crow’s foot notation relationship names appear on the line connecting the entity types involved in the relationship.
  • 5. Connectivity To describe the relationship classification Cardinality A constraint on the number of entities that participate in a relationship. Has minimum and maximum cardinality for both directions of a relationship. EXAMPLE
  • 6. MANY-TO- MANY (M-N) ONE-TO- MANY (1-M) ONE-TO- ONE (1-1)
  • 7. Classification of cardinalities  Minimum cardinality based:  A min cardinality of 1>= (one or more) indicates a mandatory relationship which creates an existence dependent  A min cardinality of 0 indicates an optional relationship  Maximum cardinality based  A max cardinality of 1 means the relationship is single- valued or functional (in math, value 1)  1-1 (less common), 1-M (common), M-N (common).
  • 8. Summary of Cardinalities
  • 9. Type of entity Type of attribute Relationship strength Degree of relationship
  • 10. • The entity is existence independent Strong entity • The entity is existence dependent Weak entity
  • 11. Strong relationship • Identifying relationship • Exist when PK of related entity contains PK component of parent entity Weak relationship • Non-identifying relationship • Exist if PK of related entity does not contain PK component of parent entity
  • 12. Example Weak relationship but strong entity strong relationship but weak entity
  • 13. Attribute Composite attribute Simple attribute Single value attribute Multivalu ed attribute Derived attribute Definition Attribute that can be further subdivided to yield additional attribute Attribute that cannot be subdivided Attribute that can have only a single value Attribute that can have many value Attribute whose value is calculated from other attribute Example Address ( street, city, zip code, state) age, sex, marital status social security number, ic number level of education, car’s color An emp_age, May be found by compUting the integer value of the different between the current date and the emp_dob
  • 14. Degree of Relationships  Unary Exist when an association is maintained within a single entity. Binary Exist when two entities are associates in a relationship.  Ternary and higher-degree relationship Three entities are associates and higher-order relationship does allow the designer some latitude regarding the semantic of a problem.
  • 15. SPECIALIZATION/GANERALIZATION  Concepts of specialization/generalization is associated with special types of entities known as SUPERCLASSES SUBCLASSES And the process of  ATTRIBUTE INHERITANCE
  • 16. SUPERCLASS • Entity type that have one or more distinct subgrouping of it occurrences, which must be represented in a data model SUBCLASS • A distinct subgrouping occurrences of an entity type, which must be represented in a data model.
  • 17. SUPERCLASS/SUBCLASS RELATIONSHIP  Each member of a subclass is also a member of the superclass. In other word the entity in subclass is the same entity in superclass, but have distinct role.  It has one to one relationship( superclass/ subclass relationship)  E.g: Staff/Manager has superclass/subclass relationship.
  • 18. EXAMPLES STAFF MANAGER SALES PERSONNEL SECRETARY SUPERCLASS SUBCLASS
  • 19. ATTRIBUTE INHERITANCE  An entity in a subclass represent the same ‘real world’ object in the superclass.  E.g: A member of the SALES PERSONAL inherit all the attribute of the STAFF superclass such as (staffno, name, position, salary) and together with those sales PERSONAL SUBCLASS (sales area,car allowance)
  • 20. GENERALIZATION/SPECIALIZATION  To make the generalization/specialization we should identify first their distinguish characteristics and common characteristics for the attribute that we want to make generalization.  Hence, when we know both of them we can separate the attribute that have common characteristic in superclass while their different characteristic in every subclass.
  • 21. GANERALIZATION SPECIALIZATION •The process of minimizing the differences between entities by identifying their common characteristic. •The process of maximizing the difference between members of entity by identifying their distinguishing characteristic. •The bottom-up process of identifying a higher level, more generic entity superclass from lower level entity subclass. •The top-down process of identifying lower level, more specific entity subtype from a higher level entity super type.
  • 22. CONSTRAINT ON SPECIALIZATION OR GANERALIZATION DISJOINTNESS CONSTRAINT COMPLETENESS CONSTRAINT •DEF: means that the subtypes in a generalization hierarchy do not have any entities in common •DEF: means that every entity of super type must be an entity in one of the subtypes •It can be symbolized by : D •It can be symbolized by: C
  • 23. Staff StaffNo(PK) Name Position Salary Branch BranchNo(PK) Address Street City postcode HAS 1,1 1,M Lets assume that we have this entity type. For the position attribute (STAFF)it will have manager, clerk ,cleaner, sales personnel and etc. Hence for maximizing the difference between members of entity ,we identifying their distinguishing characteristic. The process called as generalization. GANERALIZATION
  • 24. Staff StaffNo(PK) Name Position Salary Branch BranchNo(PK) Address Street City postcode HAS 1,1 1,M Manager mgStartDate bonus SalesPersonnel salesArea carAllowance Secretary typingSpeed {D,C} Distinguishing characteristic GANERALIZATION
  • 25. Manager Staff_no Salary mgStartDate Bonus SalesPersonnel Staff_no Salary salesArea carAllowance Branch BranchNo(PK) Address Street City postcode 1,1 1,1 manages Product Prod_no(PK) Expired_dte Prod_name 1,M 1,1 sales by Lets assume that we have this entity type. For the manager and sales personnel ,we can see that they have the same characteristics(attribute). Hence we can minimizing the differences by creating the other entity. The process called as specialization. SPECIALIZATION COMMON CHARACTERISTICS
  • 26. Manager Staff_no Salary mgStartDate Bonus SalesPersonnel Staff_no Salary salesArea carAllowance Staff StaffNo(PK) Name Position Salary {D,C} Branch BranchNo(PK) Address Street City postcode Product Prod_no(PK) Expired_dte Prod_name manages sales by SPECIALIZATION
  • 27. Branch BranchNo(PK) Address Street City postcode Staff StaffNo(PK) Name Position Salary has 1..1 1..* PartTimeTemporary hourlyRate FullTimePermanent salaryScale holidayAllowance Secretary typingSpeed SalesPersonnel salesArea carAllowance Manager mgStartDate bonus 1..1 1..1 manages { C} {D, C} disjointness constraint Indicate specialization/ generalization Job role subclasses Contract employment subclasses EXAMPLE
  • 28. Business Rule
  • 29. Step for representation  Find the entity  Primary key  Name the relationship of the connection among business entity  Know the connection between two entity (1-m, 1-1, m-n)  Find the cardinalities- restrict number of related entities in a business situation  Generalization hierarchies- classification of business entities and organizational policies.