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Database Design, Logical Design, 1.Conceptual Design, Physical Design -…

- - - - Domain constraints
      - entity integrity constraint
      - referential integrity constraint
      - Enterprise constraints
- - - - is a concise way of representing the data requirements of the problem at hand
      - A way of finding out what you know and don’t know about that problem
      - A means of discussing the problem domain with the client, during requirements determination
    - - Types of Cardinalty
        
        1:1
        
        1:N(1 to many)
        
        NOTE: study how to draw 3 tables to represent many to many relationships
        
        M:N (many to many)
      - what is Maximum Cardinality
        
        the maximum number of occurrences of one entity that are associated with a single occurrence of the other
    - - Supertypes represent general concepts, and subtypes represent more specific variations or specializations of those concepts
        
        Example....
        
        Faculty of Information Technology is a super type while lecturer of Database is a subtype
    - - Entities and Attributes
        
        Entities will become tables while attributes become the colums of the tables when the ERD is converted into a table/database
      - Relationships
        
        Entities can be associated with one another in relationships
        a relationship can involve one, two (most usually), or more entities
        
        examples
        
        A CUSTOMER places an ORDER
        
        A STUDENT enrols in a UNIT OFFERING
        
        An EMPLOYEE works in a DEPARTMENT