M&IB Devx - Database

30 Questions | Total Attempts: 77

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M&IB Devx - Database

This is part of the DevX course assessment that will be taken by delegates before and after the programme.


Questions and Answers
  • 1. 
    The first normal form (1NF) ensures that?
    • A. 

      All attributes of a table are dependent on the entire primary key

    • B. 

      All attributes are atomic, i.e. there are no repeating groups of data

    • C. 

      All integrity constraints are met

    • D. 

      All foreign keys are identified

  • 2. 
    Which of the following describes a primary key?
    • A. 

      A primary key uniquely identifies a row in a table

    • B. 

      A primary key is the only key in that table

    • C. 

      A primary key must always be a single column

    • D. 

      Primary keys are not required in most databases

  • 3. 
    Which of the following statements best describes "isolated", the "I" in ACID?
    • A. 

      Transactions complete in one complete unit of work, or not at all.

    • B. 

      Databases limit the number of concurrent users.

    • C. 

      A transaction's effect is not visible to another transaction.

    • D. 

      Databases must use ANSI-compliant SQL

  • 4. 
    Which best describes the relationship between the normal forms?
    • A. 

      Each normal form is independent from the others and may be applied selectively

    • B. 

      Higher normal form (e.g. 3NF) are dependent upon lower normal forms (e.g 1NF)

    • C. 

      Lower normal form (e.g. 1NF) are dependent upon higher normal forms (e.g 3NF)

    • D. 

      Higher normal forms guarantee better performance

  • 5. 
    What are the four attributes of an A.C.I.D. transaction?
    • A. 

      Atomic, Consistent, Isolated and Durable

    • B. 

      Atomic, Coherent, Immediate and Dependable

    • C. 

      Atomic, Consistent, Immediate and Dependable

    • D. 

      Atomic, Coherent, Isolated, Durable

  • 6. 
    A primary key that consists of two or more columns is called?
    • A. 

      Surrogate

    • B. 

      Generated

    • C. 

      Composite

    • D. 

      Complex

  • 7. 
    Which THREE of the following are benefits of data normalization?
    • A. 

      Clearer data relationships

    • B. 

      Ease of adding data

    • C. 

      Flexible data structure

    • D. 

      Creates the database design

  • 8. 
    In a database, a Foreign Key is used for which of the following?
    • A. 

      To make a relationship from an attribute in a table to the primary key of another table

    • B. 

      To internationalize a primary key value

    • C. 

      To enforce an optimistic locking strategy

    • D. 

      To combine multiple primary key values into a single key

  • 9. 
    Set theory implies which of the following is true of a database?
    • A. 

      All tables have required ordering

    • B. 

      Null values may never exist

    • C. 

      Each row in the table is unique

    • D. 

      The database must be in at least 2NF

  • 10. 
    Which is these is a definition of a correlated subquery?
    • A. 

      A subquery which references a table in the outer query

    • B. 

      A subquery which references an outer join

    • C. 

      A subquery which references an inner join

    • D. 

      None of the above

  • 11. 
    Which THREE of the following are true about bulk processing?
    • A. 

      Is a form of array processing

    • B. 

      Reduces performance when processing a large number of rows

    • C. 

      Allows a statement to process many rows

    • D. 

      Fetches rows into a collection

  • 12. 
    Which TWO of these are a reason to use database-specific features?
    • A. 

      Useful for scalar functions

    • B. 

      Upskills developers for that database

    • C. 

      Makes it easier to port queries

    • D. 

      Gets the best value out of our databases

  • 13. 
    An explain plan shows how a statement was actually processed
    • A. 

      True

    • B. 

      False

  • 14. 
    All columns that are part of primary and unique keys are indexed automatically
    • A. 

      True

    • B. 

      False

  • 15. 
    Each index used on a table decreases performance of Delete statements on that data
    • A. 

      True

    • B. 

      False

  • 16. 
    Partitioning cannot be changed once it is implemented
    • A. 

      True

    • B. 

      False

  • 17. 
    When do you design for database performance?
    • A. 

      Once the system has run and you have relaible performance statistics

    • B. 

      Just before the system is released into UAT

    • C. 

      Up front as part of the database design process

    • D. 

      None of the above

  • 18. 
    Object-relational mapping tools present a table-centriic view of the database to application developers.
    • A. 

      True

    • B. 

      False

  • 19. 
    What is the purpose of the Data Access Object (DAO) pattern?
    • A. 

      To cache data that has previously been accessed from the database

    • B. 

      To ensure transactional concurrency

    • C. 

      To enforce referential integrity

    • D. 

      To encapsulate database access

  • 20. 
    PL/SQL variables are bind variables
    • A. 

      True

    • B. 

      False

  • 21. 
    Which TWO of following two approaches may be used to prevent SQL Injection attacks?
    • A. 

      Use bind variables

    • B. 

      Validate inputs

    • C. 

      Use dynamic queries

    • D. 

      Careful construction of SQL statements

  • 22. 
    Each entry in an index points to a unique row in a table
    • A. 

      True

    • B. 

      FALSE

  • 23. 
     Reverse key indexes can be used to reduce contention on index blocks in high volume OLTP systems where the primary key is a sequence of numbers.
    • A. 

      True

    • B. 

      False

  • 24. 
    Full table scans should always be avoided, as they yield poorer performance than using an index.
    • A. 

      True

    • B. 

      False

  • 25. 
    Which index type often works well for data that is not highly selective, such as boolean values?
    • A. 

      A reverse-key index

    • B. 

      A balanced B-tree

    • C. 

      A function index

    • D. 

      A bitmapped index

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