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Unit 2 Exploring Databases and SQL

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Knowledge Check: Relational Algebra 1

  1. Given two tuple sets (A with 10 elements and B with 5 elements), what is the maximum number of tuples in the union of these sets?
  • 10
  • [Correct] 15 (The maximum number of tuples is achieved when there are no common elements between A and B)
  • 5
  • 50
  1. Which mathematical operator must be used in order to display information about students who are majoring in Computer Science but not in Electrical Engineering?
  • [Correct] Difference (The difference operator displays the requested information)
  • Intersection
  • Union
  • Cartesian Product
  1. Which statement about the selection operator is true?
  • [Correct] It filters certain tuples in a relation based on given criteria. (This is the function of the selection operator)
  • It filters certain attributes in a relation based on given criteria.
  • It requires more than one relation as its input.
  • It requires more than one database as its input.

Knowledge Check: Relational Algebra 2

  1. Consider a relation, STUDENT, with the following attributes: Name, ID number, Major, Graduation Year, and GPA. Consider a query using this relation: “List the names and ID numbers of students majoring in Computer Science.” Which operator is absolutely necessary for this query?
  • Intersection
  • Union
  • Difference
  • [Correct] Projection (The projection operator is necessary to display the two attributes, name, and ID number, in the query)
  1. Consider two sets: A with 10 tuples, and B with 5 tuples. What is the maximum number of tuples that the intersection of A and B can have?
  • 15
  • [Correct] 5 (The number of tuples in the intersection must be less than the minimum number of tuples in A and B)
  • 50
  • 10
  1. What is the ϴ-Join operation used for?
  • To join two tuples in the same relation.
  • To join two attributes in the same relation.
  • To join two databases.
  • [Correct] To join two relations in a database.

Screen Shot 2021-10-02 at 10 00 51 PM

  1. Which statement about the selection operator is correct?
  • It displays certain tuples based on given criteria. (This is the output of the selection operator)
  • It displays certain attributes based on given criteria.
  • It requires more than one relation.
  • It requires more than one attribute.

Unit 1 & 2: Graded Quiz

  1. Which of the following is NOT one of the levels of abstraction for databases?
  • Physical Schema
  • Conceptual Schema
  • [Correct] Filesystem Schema
  • Views
  1. Table descriptions are an example of ______ level documentation.
  • Physical Schema
  • Views
  • Filesystem Schema
  • [Correct] Conceptual Schema
  1. A particular query that pulls information from one or more tables is an example of a:
  • [Correct] View
  • Conceptual Schema
  • Physical Schema
  • Relation
  1. Which of the following database types is most oriented toward storing well-structured data?
  • NoSQL Database
  • Hadoop
  • [Correct] Relational Database
  • Spark
  1. What major advantage do NoSQL database systems have?
  • [Correct] NoSQL database systems can deal with unstructured data
  • NoSQL database systems data is highly structured
  • NoSQL database systems bundle massive scale well
  • NoSQL database systems are good for operational data.
  1. In an ER Diagram, a diamond shape indicates what?
  • An attribute
  • [Correct] A relationship
  • A constraint
  • An entity
  1. A participation constraint is indicated how in an ER diagram.
  • A dotted line
  • A dashed line
  • A line
  • [Correct]A bold line
  1. Consider the query: ∏𝑎,𝑏(𝜎𝑐=2(𝑧∪𝑦)) What does the query return?
  • [Correct] Fields a and b of the rows from z and y where c=2.
  • Fields a, b, c or the rows from the intersection of z and y where c=2.
  • Fields a,b, and c of the rows from y and z where c=2.
  • Fields a and b of the rows from the intersection of z and y where c=2.
  1. What does the relational algebra operator ‘x’ indicate?
  • The union of the two tables.
  • [Correct] All possible pairs from the two tables.
  • All pairs from the two tables matched on a specified field.
  • The intersection of the two tables.
  1. Of the three elements in the basic SQL query, which is the only optional one?
  • FROM
  • [Correct] DISTINCT
  • SELECT
  • WHERE
  1. Massive scale analytics merely require which type of database system?
  • [Correct] Hadoop, Spark, or similar
  • MongoDB
  • Oracle
  • NoSQL
  1. The basic formula for an SQL query is:
    [Correct] SELECT, FROM, WHERE
    TARGET, RELATION, DISTINCT
    DISTINCT, FIELD, ID
    DISTINCT FROM QUALIFICATION