E/R MODELLING Terminology, Keys and Weak Entities

  1. Can you name & explain each name part of a table?
    Domains 
    Attributes
    Attribute Values
    Tuple
    Degree
    Cardinality
    • Domains can restrict the allowed attribute values
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  2. What is functional dependencies?
    What is a valid function dependency and what is not?
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    Functional dependency, If two rows(r1),(r4) in a column(SSN) has the same attribute(111) then they must also have the same tributes(SMITH) in the other column(LAST) to be funtionaly dependent.Does the X determine they y? if x and y is known can u go to ever x and get the same y? if not then not dependent.
  3. What are keys in the ER model?
    Example?
    many?
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  4. When and why does week entity exist?
    Why is a relationship involved?
    Give example of a week relationship with two entitis and total of 3 attributes.
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  5. ER diagrams vs. EER diagrams whats the differance and what do they contain?
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Author
ccc
ID
352205
Card Set
E/R MODELLING Terminology, Keys and Weak Entities
Description
E/R MODELLING Keys and Weak Entities
Updated