Get WGU Data Management - Foundations Exam Practice Questions - Real and Updated

Answer : A

The UNION keyword in SQL is used to combine the results of two or more SELECT queries into a single result set while removing duplicate rows.

Example:

sql

SELECT Name FROM Employees

UNION

SELECT Name FROM Managers;

Option A (Correct): UNION combines results from multiple queries into one set, removing duplicates.

Option B (Incorrect): MERGE is not a valid SQL keyword for combining result sets (it is used in some database systems for data merging).

Option C (Incorrect): INTEGRATE is not a SQL keyword.

Option D (Incorrect): CONSOLIDATE is not an SQL keyword.

Answer : A

A simple primary key consists of only one column that uniquely identifies each row in a table.

Example Usage:

sql

CREATE TABLE Students (

StudentID INT PRIMARY KEY,

Name VARCHAR(50)

);

StudentID is a simple primary key because it consists of only one field.

Why Other Options Are Incorrect:

Option B (Partition) (Incorrect): Refers to partitioned tables, which divide data for performance reasons but are not related to primary keys.

Option C (Stable) (Incorrect): This is not a recognized term in database keys.

Option D (Meaningless) (Incorrect): Primary keys are often meaningless (e.g., auto-incremented IDs), but this is not a term used to describe their structure.

Thus, the correct answer is Simple, as a single-field primary key is referred to as a simple primary key.

Answer : B

The first step in database analysis is identifying entities, which are the real-world objects that need to be represented in the database.

Example Usage:

In a school system, the main entities could be:

Students, Courses, Instructors

Why Other Options Are Incorrect:

Option A (Determine cardinality) (Incorrect): Determining relationships comes after identifying entities.

Option C (Draw an ER diagram) (Incorrect): ER diagrams visualize entities but are not the first step.

Option D (Implement attributes) (Incorrect): Attributes are defined after entities are identified.

Thus, the correct answer is Identify entities, as entities form the foundation of the database model.

Answer : C

This query performs a join operation where records from the Make table and Model table are combined based on the condition Make.ModelID = Model.ID. This condition tests for equality, which is the definition of an EQUIJOIN.

Types of Joins in SQL:

EQUIJOIN (Correct Answer):

Uses an equality operator (=) to match rows between tables.

Equivalent to an INNER JOIN ON condition.

Example:

sql

SELECT *

FROM Employees

JOIN Departments ON Employees.DeptID = Departments.ID;

NON-EQUIJOIN (Incorrect):

Uses comparison operators other than = (e.g., <, >, BETWEEN).

Example:

sql

SELECT *

FROM Employees e

JOIN Salaries s ON e.Salary > s.MedianSalary;

SELF JOIN (Incorrect):

A table is joined with itself using table aliases.

Example:

sql

SELECT e1.Name, e2.Name AS Manager

FROM Employees e1

JOIN Employees e2 ON e1.ManagerID = e2.ID;

CROSS JOIN (Incorrect):

Produces Cartesian product (each row from Table A combines with every row from Table B).

Example:

sql

SELECT *

FROM Employees

CROSS JOIN Departments;

Thus, since our given query uses an equality condition (=) to join two tables, it is an EQUIJOIN.

Answer : B

A unary relationship (also known as a recursive relationship) occurs when an entity relates to itself.

Example Usage:

Employees and Managers:

sql

CREATE TABLE Employees (

EmpID INT PRIMARY KEY,

Name VARCHAR(50),

ManagerID INT,

FOREIGN KEY (ManagerID) REFERENCES Employees(EmpID)

);

Here, ManagerID references another Employee a unary (self-referential) relationship.

Why Other Options Are Incorrect:

Option A (Modality) (Incorrect): Describes optional vs. mandatory relationships, not self-referencing.

Option C (Cardinality) (Incorrect): Defines how many instances relate, not the type of relationship.

Option D (Binary) (Incorrect): Binary relationships involve two different entities, not self-referencing.

Thus, the correct answer is Unary, as it describes relationships within the same entity type.