Statistics > EXAM > Summary Handbook Statistics Final Exam (CIS) Questions and Answers 2023 (All)

Summary Handbook Statistics Final Exam (CIS) Questions and Answers 2023

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entity supertype - -contains common characteristics -entity subtypes - -each contain their own unique characteristics -example supertype - -EMPLOYEE is the supertype of PILOT -example subtype... s - -PILOT is a subtype of EMPLOYEE -inheritance - -enables an entity subtype to inherit the attributes and relationships of the supertype (primary key) -subtype discriminator - -is the attribute in the supertype entity that determines to which subtype the supertype occurrence is related -Disjoint subtypes - -entity instance of the supertype can appear in only one of the subtypes -Overlapping subtypes - -entity instance of the supertype may appear in more than one subtype -Example : Overlapping subtypes - -in a university environment, a person may be an employee, a student, or both -completeness constraint - -specifies whether each entity supertype occurrence must also be a member of at least one subtype -Partial completeness - -means that not every supertype occurrence is a member of a subtype; some supertype occurrences may not be members of any subtype -Total completeness - -means that every supertype occurrence must be a member of at least one subtype. -Desirable Primary Key Characteristics - -1.Unique values, 2.Nonintelligent 3.No change over time, 4. Preferably single-attribute 5.Preferably numeric 6.Security-compliant -Unique values - -A primary key must be able to guarantee unique values. It cannot contain nulls. -Nonintelligent - -The PK should not have embedded semantic meaning -No change over time - -the PK should be permanent and [Show More]

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