CS6400 - Exam 2 Questions with Detailed Verified Answers
attribute
Ans: column header
tuple
Ans: a row in a table
relation
Ans: table
domain
Ans: types of values that can appear in each column
degree (or arity) of a relation
Ans: number of attributes of its relationship schema
self-describing data
Ans: when the attribute name and value are included together in a tuple
For example t = <(Address, 3452 Elgin Road), (Name, Dick Davidson), (Ssn, 422-11-
2320), (Age, 25), (Office_phone, (817)749-1253), (Gpa, 3.53), (Home_phone,NULL)>
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Flat relational model
Ans: each value in each tuple is atomic, so it is not divisible into components within
the framework of the basic relational model. Hence, composite and multivalued
attributes are not allowed.
This assumption is also called the first normal form assumption.
inherent model-based constraints or implicit constraints
Ans: constraints that are inherent in the data model
schema-based constraints or explicit constraints
Ans: constraints that can be directly expressed in the schemas of the data model,
typically by specifying them in the DDL
application-based or semantic constraints
Ans: constraints that cannot be directly expressed in the schemas of the data model,
and hence must be expressed and enforced by the application programs or in some
other way
domain constraints
Ans: A set of restrictions on the values allowed for the attributes of relations
e.g., integer, float, booleans, fixed-length strings
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