Data-Management-Foundations WGU Data Management – Foundations Exam Questions and Answers

In SQL,literalsrepresent explicit values such asnumbers, strings, or binary datadirectly written into queries. For example:

SELECT * FROM Employees WHERE Salary > 50000;

Here, 50000 is anumeric literal.

Option A (Correct):Literalsare explicit values used in SQL queries, such as 123, 'John Doe', and TRUE.

Option B (Incorrect):Commentsare non-executable text used for documentation within SQL code, typically denoted by -- or /* ... */.

Option C (Incorrect):Identifiersare names oftables, columns, or other database objects, such as EmployeeID.

Option D (Incorrect):Keywordsare reserved words in SQL (e.g., SELECT, FROM, WHERE) that define operations and syntax.

Aunary relationship(also known as arecursive relationship) occurs when an entityrelates 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, ManagerIDreferences another Employee→ aunary (self-referential) relationship.

Why Other Options Are Incorrect:

Option A (Modality) (Incorrect):Describesoptional vs. mandatoryrelationships, not self-referencing.

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

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

Thus, the correct answer isUnary, as it describesrelationships within the same entity type.

Arelationshipin an ER model defineshow two separate entities interact.

Example Usage:

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CREATE TABLE Customers (

CustomerID INT PRIMARY KEY,

Name VARCHAR(50)

);

CREATE TABLE Orders (

OrderID INT PRIMARY KEY,

CustomerID INT,

FOREIGN KEY (CustomerID) REFERENCES Customers(CustomerID)

);

Customers and Orders are separate entities, related via CustomerID.

Why Other Options Are Incorrect:

Option A (Reflexive relationship) (Incorrect):Used forself-referencing entities, not two different entities.

Option B (Entity type) (Incorrect):Defines aclass of objects, but does not establish relationships.

Option D (Attribute) (Incorrect):Attributesdescribeentities but do not connect them.

Thus, the correct answer isRelationship, as it connectstwo separate entities.

TheHAVINGclause is used in SQL to filtergrouped resultsgenerated by the GROUP BY clause. Unlike WHERE, which filters individual rowsbeforegrouping, HAVING filtersafter aggregationhas been performed.

Example Usage:

sql

SELECT Department, AVG(Salary) AS AvgSalary

FROM Employees

GROUP BY Department

HAVING AVG(Salary) > 50000;

This query first groups employees by Department, calculates theaverage salary per department, and then filters onlythose departments where the average salary is greater than 50,000.

Why Other Options Are Incorrect:

Option A (REPLACE) (Incorrect):Used for string substitution, not filtering.

Option C (WITH) (Incorrect):Used inCommon Table Expressions (CTEs), not for filtering.

Option D (WHERE) (Incorrect):Used forrow-level filtering before aggregation, but itcannot be used on aggregate functions like SUM() or AVG().

Thus,HAVING is the correct answerfor filtering after grouping.

Databases need to supportApplication Programming Interfaces (APIs)to enable seamless integration withgeneral-purpose programming languageslike Python, Java, and C#. APIs likeODBC (Open Database Connectivity) and JDBC (Java Database Connectivity)allow applications to interact with databases without requiring complex SQL commands.

Option A (Incorrect):Thestorage manageris responsible for managing low-levelfile system operations, but it does not simplify SQL integration with programming languages.

Option B (Incorrect):The ability toreverse results(e.g., using ORDER BY DESC) is a SQL feature but is unrelated to integration with programming languages.

Option C (Incorrect):Thequery processoroptimizes and executes SQL queries but does not provide an interface for application development.

Option D (Correct):APIsallow databases to be accessed easily from different programming environments, simplifying integration.

Anintangible entityis an entity that does not have a physical presence but still holds meaning in a database. These entities representconcepts, relationships, or abstract datathat exist in a logical sense.

Example Usage in Databases:

Customer Loyalty Status (Gold, Silver, Bronze)

Theloyalty levelis anintangible entitysince it is derived from other data (purchase history).

Online User Sessions

Asession IDexistslogically in the systembut does not have a tangible presence like a product or employee.

Why Other Options Are Incorrect:

Option A (Concrete entity) (Incorrect):No such formal term in database design.

Option B (Tangible entity) (Incorrect):Represents somethingphysical, like anemployeeorproduct.

Option D (Physical entity) (Incorrect):Refers todata stored on disk, like database tables or indexes.

Thus, the correct answer isIntangible entity, as it only exists in a logical sense within the database.

TheALTER TABLEstatement is used to modify an existing database table structure. One common clause isCHANGE, which allows renaming a column and modifying its data type.

Example:

sql

ALTER TABLE Employees CHANGE COLUMN OldName NewName VARCHAR(50);

Option A (Incorrect):DELETE is used to removerows, not alter table structure.

Option B (Correct):CHANGE is avalid clausefor renaming and modifying columns in MySQL and some other databases.

Option C (Incorrect):STOP is not a valid SQL keyword for altering tables.

Option D (Incorrect):AGGREGATE refers to functions like SUM() and AVG(), not table alterations.

Areflexive relationship(also called aunary relationship) occurs when anentity is related to itself.

Example Usage:

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CREATE TABLE Employees (

EmpID INT PRIMARY KEY,

Name VARCHAR(50),

ManagerID INT,

FOREIGN KEY (ManagerID) REFERENCES Employees(EmpID)

);

ManagerIDrefers to another employeewithin the same table.

Why Other Options Are Incorrect:

Option A (Repository) (Incorrect):A data storage structure, not a relationship type.

Option B (Relationship instance) (Incorrect):Describesa specific connection between entities, not a reflexive relationship.

Option D (Attribute) (Incorrect):Attributes storecharacteristics, butdo not define relationships.

Thus, the correct answer isReflexive relationship, as it relates an entity to itself.

The % operator in MySQL is known as themodulus operator. It returns theremainderof a division operation between two numbers.

Example:

sql

SELECT 10 % 3; -- Output: 1 (10 divided by 3 gives remainder 1)

Option A (Incorrect):Raising a number to a power is done using the POW() function or ^ in some SQL dialects.

Option B (Incorrect):The = operator is used forequality comparisons, not %.

Option C (Correct):Themodulus operator (%)finds the remainder when one number is divided by another.

Option D (Incorrect):Subtraction is performed using the - operator.

Thefirst stepin database analysis isidentifying entities, which are thereal-world objectsthat need to be represented in the database.

Example Usage:

In a school system, the mainentitiescould be:

Students, Courses, Instructors

Why Other Options Are Incorrect:

Option A (Determine cardinality) (Incorrect):Determining relationships comesafteridentifying entities.

Option C (Draw an ER diagram) (Incorrect):ER diagramsvisualizeentities but arenot the first step.

Option D (Implement attributes) (Incorrect):Attributes aredefined afterentities are identified.

Thus, the correct answer isIdentify entities, asentities form the foundation of the databasemodel.

When performing aJOIN operationin MySQL, the ON clause specifies thejoining condition, defining which columns from both tables should be matched.

Example:

sql

SELECT Employees.Name, Departments.DepartmentName

FROM Employees

JOIN Departments ON Employees.DepartmentID = Departments.ID;

Option A (Incorrect):AS is used foraliasing tables and columns, not for specifying join conditions.

Option B (Incorrect):JOIN defines the type of join (INNER JOIN, LEFT JOIN, etc.), butdoes not specify the columns.

Option C (Correct):The ON clause is used tospecify the join conditionbetween two tables.

Option D (Incorrect):AND is used in filtering conditions, not for joining tables.

Thecorrect syntaxfor deleting records from a table in SQL is:

sql

DELETE FROM table_name WHERE condition;

This deletesonly the rowsthat match the condition.

Example Usage:

sql

DELETE FROM Employees WHERE Salary < 30000;

Deletesall employees earning less than $30,000.

Why Other Options Are Incorrect:

Option A (Incorrect):Missing FROMkeyword. The correct syntax is DELETE FROM table_name.

Option C (Partially Correct):DELETE FROM table_name;deletes all rows, but it lacks a WHERE clause.

Option D (Incorrect):DELETE *is not validin SQL. The correct command is just DELETE FROM.

Thus, the correct answer isDELETE FROM table_name WHERE condition;.

Bydatabase design conventions, theprimary key is usually placed in the first columnof a table to make it easy to identify and reference.

Example Usage:

sql

CREATE TABLE Employees (

EmpID INT PRIMARY KEY, -- First column (convention)

Name VARCHAR(50),

Salary DECIMAL(10,2)

);

EmpID is placed as the first columnfor clarity and quick access.

Why Other Options Are Incorrect:

Option A (In the table header) (Incorrect):Table headers onlydisplay column names, they do not contain values.

Option C (In the top row) (Incorrect):Thetop row contains data, not theprimary key definition.

Option D (In the last visible column) (Incorrect):While technically possible,placing a primary key at the endisuncommonin database design.

Thus, the correct answer isIn the first column, as this is the standard convention in relational databases.

Adata typedefines the kind of data a column can store in a database. It ensures data consistency and efficient storage.

Option A (Correct):A data type is anamed set of values, such asINTEGER, VARCHAR, DATE, etc.

Option B (Incorrect):A tuple refers to arowin a relational database, not a data type.

Option C (Incorrect):Data typesdefinecolumn values, but they do not correspond directly to columns.

Option D (Incorrect):Data types do not have avaryingset of rows; they define attributes for columns.

Indatabase design,attributesof an entity becomecolumnsin a relational table.

Example Usage:

For anEmployee entity, attributes might include:

CREATE TABLE Employees (

EmployeeID INT PRIMARY KEY,

Name VARCHAR(50),

Salary DECIMAL(10,2),

DepartmentID INT

);

Eachattribute(e.g., Name, Salary) becomes acolumnin the table.

Why Other Options Are Incorrect:

Option A (Modality) (Incorrect):Describesoptional vs. mandatoryrelationships, not table structure.

Option B (Uniqueness) (Incorrect):Ensuresdistinct valuesbutis not a column property.

Option D (Non-null values) (Incorrect):Ensures thatcolumns must contain databut doesnot define attributes.

Thus, the correct answer isAttribute, as attributes of entities becometable columns.