WGU D426 DATA MANAGEMENT FOUNDATIONS OA PRACTICE TEST, Exams of Database Management Systems (DBMS)

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Answer: B. Conceptual design Rationale: Conceptual design is a high-level, system- independent model that defines entities, attributes, and relationships without considering any specific DBMS.

Q3. What characterizes the rules of relational databases? A. They are logical constraints that ensure the data is valid B. They are based on business policy and specific databases C. They represent data volumes and rapidly changing data structures D. They embody the theoretical foundation of the SQL language Answer: A. They are logical constraints that ensure the data is valid Rationale: Relational database rules are logical constraints that ensure data validity through integrity rules like entity integrity and referential integrity.

Q4. In a scenario where a database designer is tasked with creating a new database for a retail company, what should they prioritize before defining supertype and subtype entities? A. Implementing security measures B. Identifying entities

C. Designing the user interface D. Choosing the database management system Answer: B. Identifying entities Rationale: Before defining supertype and subtype relationships, the designer must first identify all entities that will be part of the database model.

Q5. When a database stores the majority of data in RAM rather than on hard disks, it is referred to as a(n): A. Big Data database B. In-memory database C. Very large database D. Cloud database Answer: B. In-memory database Rationale: An in-memory database stores data primarily in RAM for faster access, as opposed to disk-based storage.

Q6. What is the primary purpose of a database? A. To store files on a hard drive

Q8. Which of the following best describes the three levels of database design? A. External, Internal, and Conceptual B. Physical, Logical, and Conceptual C. Operational, Analytical, and Strategic D. Development, Testing, and Production Answer: B. Physical, Logical, and Conceptual Rationale: The three levels of database design are Conceptual (high-level, system-independent), Logical (more detailed, still DBMS-independent), and Physical (implementation-specific).

Q9. What does modality refer to in an Entity-Relationship (ER) diagram? A. The maximum number of times an instance in one entity can be associated with another B. The minimum number of times an instance in one entity can be associated with another C. The data type of an attribute D. The primary key of an entity

Answer: B. The minimum number of times an instance in one entity can be associated with another Rationale: Modality refers to the MINIMUM number of times an instance in one entity can be associated with an instance in another entity. It appears as a 0 or 1 on the relationship line.

Q10. Cardinality in an ER diagram refers to: A. The minimum number of relationships B. The maximum number of relationships C. The data type of the relationship D. The name of the relationship Answer: B. The maximum number of relationships Rationale: Cardinality specifies the maximum number of times an instance in one entity can be associated with instances in another entity (e.g., 1:1, 1:M, M:N).

Q11. A "consumer of data in a database" who can either use an application or submit queries directly to the database is called a(n): A. Database administrator B. End user

C. Select Query Language D. Object Query Language Answer: B. Structured Query Language Rationale: SQL (Structured Query Language) is the standardized language used to interact with relational database systems.

**Q14. Which SQL sublanguage is used to manage database access? ** A. Data Definition Language (DDL) B. Data Query Language (DQL) C. Data Manipulation Language (DML) D. Data Control Language (DCL) Answer: D. Data Control Language (DCL) Rationale: DCL includes commands like GRANT and REVOKE to manage user permissions and database access.

Q15. Which SQL sublanguage is used to roll back database changes? A. Data Transaction Language (DTL)

B. Data Manipulation Language (DML) C. Data Query Language (DQL) D. Data Control Language (DCL) Answer: A. Data Transaction Language (DTL) Rationale: DTL (also called TCL) includes COMMIT and ROLLBACK commands to manage transactions.

Q16. Which data type should be used to store whole integer values, such as age? A. NUM B. VARCHAR C. DATE D. INT Answer: D. INT Rationale: INT is the correct data type for storing whole numbers/integers in MySQL.

Q17. Which text-based interface is included in the MySQL Server Download?

A. When the server or updates are incorrectly installed B. When an SQL statement is entered to locate errors in the database C. When an SQL statement is syntactically incorrect D. When a Mac OS shortcut code is used on a Windows OS Answer: C. When an SQL statement is syntactically incorrect Rationale: MySQL returns error codes and descriptions when an SQL statement contains syntax errors.

Q20. Which format is used by the TIME data type in MySQL? A. YYYY-MM-DD B. YYYY-MM-DD hh:mm:ss C. hh:mm:ss D. YYYY-MM-DD hh:mm:ss Answer: C. hh:mm:ss Rationale: The TIME data type in MySQL stores time values in the format hh:mm:ss.

Q21. Which MySQL operator is the last in the order of operator precedence? A. OR B. NOT C. = D. AND Answer: A. OR Rationale: In MySQL operator precedence, OR has the lowest precedence and is evaluated last.

Q22. Which operator is used to compare columns from the left and right tables in MySQL? A. <= B. + C. = D. != Answer: C. = Rationale: The equality operator (=) is used to compare columns from the left and right tables in join conditions.

Q25. Which type of join is demonstrated by the following query?

SELECT Dog.Nickname, Kennel.Address FROM Dog, Kennel WHERE Dog.KennelID = Kennel.ID

A. Non-equijoin B. Self join C. Cross join D. Equijoin Answer: D. Equijoin Rationale: This query uses the = operator to compare Dog.KennelID with Kennel.ID, making it an equijoin. Section 3: Referential Integrity and Constraints (Questions 26–35) Q26. Referential integrity requires that: A. All primary key values must be unique B. All foreign key values must either be fully NULL or match some primary key value C. All tables must have a primary key D. All columns must be indexed

Answer: B. All foreign key values must either be fully NULL or match some primary key value Rationale: Referential integrity ensures that foreign key values either match an existing primary key value in the referenced table or are NULL.

Q27. Which constraint propagates primary key changes to foreign keys? A. RESTRICT B. SET DEFAULT C. CASCADE D. SET NULL Answer: C. CASCADE Rationale: The CASCADE constraint ensures that updates or deletions in the primary key table automatically reflect in the foreign key table.

Q28. Which action rejects an insert, update, or delete that would violate referential integrity? A. SET NULL B. SET DEFAULT

B. SET DEFAULT

C. RESTRICT

D. CASCADE

Answer: B. SET DEFAULT Rationale: SET DEFAULT sets invalid foreign keys to a default primary key value.

Q31. In which four ways can referential integrity be violated? A. Primary key is updated, foreign key is updated, row containing primary key is deleted, row containing foreign key is inserted B. Table is dropped, column is renamed, index is added, view is created C. Data type is changed, default value is set, constraint is added, index is removed D. All of the above Answer: A. Primary key is updated, foreign key is updated, row containing primary key is deleted, row containing foreign key is inserted Rationale: Referential integrity can be violated when: 1) a primary key is updated, 2) a foreign key is updated, 3) a row containing a primary key is deleted, or 4) a row containing a foreign key is inserted.

Q32. An important aspect of referential integrity is that: A. All tables must have at least one foreign key B. Reference to data in one relation is based on values in another relation C. All primary keys must be integers D. Foreign keys cannot be NULL Answer: B. Reference to data in one relation is based on values in another relation Rationale: Referential integrity ensures that references between tables are valid by requiring that foreign key values correspond to existing primary key values.

Q33. A primary key constraint ensures that: A. Values in the column are unique and not NULL B. Values in the column can be duplicated C. Values in the column are always numeric D. Values in the column reference another table Answer: A. Values in the column are unique and not NULL Rationale: A primary key uniquely identifies each row in a table, requiring unique and non-NULL values.