Relational Data Model Lecture 3 Quiz
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Questions and Answers

What is the relational model based on?

  • Trees
  • Tables (correct)
  • Arrays
  • Graphs

    • In the relational model, what are the rows called?

  • Clusters
  • Sequences
  • Entities
  • Tuples (correct)

    • What is the name of the schema of a relation denoted by R(A1, A2,.An)?

  • Description
  • Entity
  • Relation (correct)
  • Table

    • What does each column in a relation have, which gives an indication of the meaning of the data items in that column?

    <p>Attribute name</p> Signup and view all the answers

    In the relational model, what does each attribute have?

    <p>A domain or a set of valid values</p> Signup and view all the answers

    What does the term 'domain' refer to in the context of database design?

    <p>The set of allowable values for one or more attributes</p> Signup and view all the answers

    Which statement accurately describes a 'tuple' in the context of database relations?

    <p>A tuple is an ordered set of values derived from a domain</p> Signup and view all the answers

    What does the term 'state' refer to in the context of relation in a database?

    <p>The populated table containing all possible column values</p> Signup and view all the answers

    In database design, what does 'r(R)' represent?

    <p>A specific state (or 'value') of relation R</p> Signup and view all the answers

    What is the primary role played by 'attribute name' in a domain within a relation?

    <p>It interprets the meaning of the data elements corresponding to that attribute</p> Signup and view all the answers

    In the context of database design, what does 'dom(Cust-name) is varchar(25)' represent?

    <p>The maximum length of the domain of the attribute Cust-name</p> Signup and view all the answers

    What is the significance of 'r(R) = {t1, t2, …, tn} where each ti is an n-tuple ti = where each vj element-of dom(Aj)' in the relational model?

    <p>It represents a specific state (or 'value' or 'population') of relation R</p> Signup and view all the answers

    What does the term 'formally' imply in the statement 'Given R(A1, A2,., An) r(R) ⊂ dom (A1) X dom (A2) X.X dom(An)'?

    <p>According to the structure or principles of the relational model</p> Signup and view all the answers

    What role does the attribute name play in a domain within a relation?

    <p>It designates the role played by the domain in a relation</p> Signup and view all the answers

    What does 'STATE The relation state is a subset of the Cartesian product of the domains of its attributes' imply in the context of database relations?

    <p>It represents all possible combinations of values for each attribute in a relation</p> Signup and view all the answers

    In the relational model, what mathematical concept is a relation based on?

    <p>Sets</p> Signup and view all the answers

    What is the formal term used for the data elements in each row of a relation?

    <p>Tuples</p> Signup and view all the answers

    Which paper first proposed the relational model for large shared data banks?

    <p>A Relational Model for Large Shared Data Banks</p> Signup and view all the answers

    What is the attribute name called in the formal model of the relational model?

    <p>Attribute</p> Signup and view all the answers

    What is the name of the schema of a relation denoted by R(A1, A2,.An)?

    <p>Relation R</p> Signup and view all the answers

    In the relational model, what is the informal definition of a relation?

    <p>A set of columns representing certain facts that correspond to a real-world entity or relationship</p> Signup and view all the answers

    What does the term 'domain' refer to in the context of database design?

    <p>The set of valid values for each attribute in a relation</p> Signup and view all the answers

    What is the primary role played by the 'attribute name' in a domain within a relation?

    <p>Giving an indication of the meaning of the data items in a column</p> Signup and view all the answers

    What does 'r(R)' represent in database design?

    <p>The formal model representing a relation as a collection of rows</p> Signup and view all the answers

    What is the significance of 'r(R) = {t1, t2, …, tn} where each ti is an n-tuple ti = where each vj element-of dom(Aj)' in the relational model?

    <p>It represents the relation state as a subset of the Cartesian product of the domains of its attributes</p> Signup and view all the answers

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