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Relational Model Overview
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Relational Model Overview

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Questions and Answers

What is generally represented by each row in a relational table?

  • A data value
  • A relation
  • An attribute
  • An entity occurrence (correct)

    • Which of the following statements about relational tables is true?

  • The intersection of a row and a column can contain multiple data values.
  • A table can have identical names for different columns.
  • The order of the columns affects data retrieval performance.
  • Each column must represent a distinct attribute. (correct)

    • Which characteristic of a relational table ensures that each row can be uniquely identified?

  • There must be an attribute or combination of attributes that uniquely identifies each row. (correct)
  • The table can contain multiple tuples with the same values.
  • Columns can be reordered without affecting the table's functions.
  • All values must conform to the same data format.

    • What does the attribute domain refer to in a relational table?

    <p>The range of values that a column can accept.</p> Signup and view all the answers

    How can the relational model be described in terms of data organization?

    <p>As a two-dimensional structure of intersecting rows and columns.</p> Signup and view all the answers

    What attribute in the STUDENT table would you use to identify the student's academic performance?

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

    Which attribute indicates whether a student has transferred from another institution?

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

    Which of the following indicates the student classification level in the STUDENT table?

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

    Which attribute would you use to find the number assigned to the student's academic advisor?

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

    What data type is likely used for the STU_DOB attribute in the STUDENT table?

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

    In terms of database normalization, which concept does a superkey relate to?

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

    What distinguishes a candidate key from a superkey?

    <p>A candidate key can include multiple attributes only if they uniquely identify a tuple.</p> Signup and view all the answers

    Which of the following student combinations includes only students classified as Juniors?

    <p>Walter Oblonski and Anne Smithson</p> Signup and view all the answers

    Which department does the student with the highest GPA belong to?

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

    Which of the following attributes is NOT a candidate key for the Branch relation?

    <p>Branch office name</p> Signup and view all the answers

    Which of the following statements about primary keys is true?

    <p>Every relation must have exactly one primary key.</p> Signup and view all the answers

    What is a foreign key's primary function in a relational database?

    <p>To enforce data integrity by matching with primary keys.</p> Signup and view all the answers

    How are composite keys defined in a relational context?

    <p>Keys formed by combining two or more attributes, potentially providing unique identification.</p> Signup and view all the answers

    Which staff member has the highest salary?

    <p>John White</p> Signup and view all the answers

    What is the maximum rent preference of client Mike Ritchie?

    <p>750</p> Signup and view all the answers

    Which property is listed by owner Tony Shaw?

    <p>PG36</p> Signup and view all the answers

    Which branch does property PG4 belong to?

    <p>B003</p> Signup and view all the answers

    Which client is registered at branch B005?

    <p>John Kay</p> Signup and view all the answers

    What type of property is PG16?

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

    How many properties are listed under branch B003?

    <p>4</p> Signup and view all the answers

    What is the preferred property type for client Mary Tregear?

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

    Which owner is associated with property PA14?

    <p>Joe Keogh</p> Signup and view all the answers

    Which viewing comment is associated with client Aline Stewart?

    <p>too small</p> Signup and view all the answers

    Study Notes

    Relational Model

    • The relational model was introduced by E.F.Codd in 1970.
    • It uses tables with rows and columns to represent data.
    • Each row is called a tuple.
    • Each column is known as an attribute.

    Characteristics of a Relational Table

    • Each table row represents a single entity occurrence.
    • Each table column has a distinct name.
    • All values in a column must be in the same data format.
    • Each column has a specific range of values, known as the domain.
    • The order of rows and columns does not matter to the DBMS.
    • Each table must have an attribute or a combination of attributes that can uniquely identify each row.

    Relational Keys

    • Keys provide a way to identify specific tuples in a relation.
    • A superkey uniquely identifies each tuple, but it might include unnecessary attributes.
    • A candidate key is a superkey that uses the absolute minimum number of attributes for unique identification.
    • A primary key is a selected candidate key used to uniquely identify tuples in a relation.
    • A foreign key matches the candidate key of another (possibly the same) relation, establishing a link between tables.

    Representing Relational Database Schemas

    • Schemas are used to describe the organization of a relational database.
    • They outline each table's name, attributes and relationships.

    DreamHome Database

    • The DreamHome case study includes multiple relations (tables) representing branches, staff, properties, clients, owners, viewings and registrations.
    • Examples of the database content are provided for each entity.

    Glossary

    • A relation is a table composed of columns and rows.

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    Related Documents

    Relational Model and ER Diagram part 1.pdf

    Description

    Explore the fundamental aspects of the relational model as introduced by E.F. Codd in 1970. This quiz covers the structure of relational tables, key characteristics, and the types of relational keys. Test your understanding of tuples, attributes, and unique identification methods within relational databases.

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