WGU Data Management - Foundations Exam Questions

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.

Non-relational databases (also called NoSQL databases) are designed for handling big data and unstructured data efficiently. They are optimized for horizontal scaling, making them ideal for large-scale distributed systems.

Option A (Correct): Non-relational databases are optimized for big data, handling massive volumes of data across distributed architectures.

Option B (Incorrect): NoSQL databases do not use SQL as their primary query language. They often use JSON-based queries (e.g., MongoDB).

Option C (Incorrect): Transaction-heavy applications require ACID compliance, which relational databases (SQL) handle better than NoSQL databases.

Option D (Incorrect): NoSQL databases use document, key-value, graph, or column-family storage models, not tables, columns, and rows like relational databases.

An attribute type refers to a single, specific value within a table, such as Salary, Age, or Price.

Example Usage:

CREATE TABLE Employees (

EmpID INT PRIMARY KEY,

Name VARCHAR(50),

Salary DECIMAL(10,2)

);

Salary is an attribute type with individual values for each employee.

Why Other Options Are Incorrect:

Option A (Glossary) (Incorrect): Refers to documentation, not database values.

Option B (Entity type) (Incorrect): Represents a class of objects (e.g., Employees), not individual values.

Option D (Relationship) (Incorrect): Defines connections between entities, not attributes.

Thus, the correct answer is Attribute type, as it represents an individual data value.

The ABS() function in SQL returns the absolute value of a given number, effectively measuring its distance from zero.

Example Usage:

sql

SELECT ABS(-50), ABS(50);

Result:

50 | 50

This function ensures that numbers are always positive, regardless of their original sign.

Why Other Options Are Incorrect:

Option A (CONCAT) (Incorrect): Used to combine strings (not numbers).

Option B (LOWER) (Incorrect): Converts text to lowercase, not numerical operations.

Option C (FROM) (Incorrect): Part of SELECT FROM queries, not a function.

Thus, the correct choice is ABS(), which computes the absolute value of a number.

In database design, attributes of an entity become columns in a relational table.

Example Usage:

For an Employee entity, attributes might include:

CREATE TABLE Employees (

EmployeeID INT PRIMARY KEY,

Name VARCHAR(50),

Salary DECIMAL(10,2),

DepartmentID INT

);

Each attribute (e.g., Name, Salary) becomes a column in the table.

Why Other Options Are Incorrect:

Option A (Modality) (Incorrect): Describes optional vs. mandatory relationships, not table structure.

Option B (Uniqueness) (Incorrect): Ensures distinct values but is not a column property.

Option D (Non-null values) (Incorrect): Ensures that columns must contain data but does not define attributes.

Thus, the correct answer is Attribute, as attributes of entities become table columns.