Free and Premium WGU Data-Management-Foundations Dumps Questions Answers

When a VIEW is created in SQL, users mayinsert or updatedata through that view. However, if a row is inserted or updated in such a way that itviolates the conditionof the VIEW’s WHERE clause, it can lead to inconsistencies.

Topreventsuch unwanted modifications,SQL provides the WITH CHECK OPTION clause.

How WITH CHECK OPTION Works:

Ensures thatany new data (INSERT/UPDATE) still fits within the defined constraints of the VIEW.

If a user tries to insert or update a row that would not appear in the VIEW,the operation isrejected.

Example:

sql

CREATE VIEW HighSalaryEmployees AS

SELECT * FROM Employees WHERE Salary > 50000

WITH CHECK OPTION;

Now, if someone attempts:

sql

INSERT INTO HighSalaryEmployees (ID, Name, Salary)

VALUES (101, 'Alice', 30000);

Thisfailsbecause 30000 does not satisfy Salary > 50000.

Why Other Options Are Incorrect:

Option B (Incorrect):JOIN VIEWS isnot a valid SQL clause.

Option C (Incorrect):MATERIALIZED VIEW refers tostored viewsin some databases, but it doesnotreject incorrect inserts/updates.

Option D (Incorrect):BASE TABLE refers to theoriginal table from which a VIEW is created.

Thus, the correct answer is WITH CHECK OPTION, whichensures that only valid data modifications occur.

Arelationshipin an ER model defineshow two separate entities interact.

Example Usage:

A screenshot of a computer AI-generated content may be incorrect.

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.

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.

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.

Cardinalitydefines theminimum and maximum number of occurrencesof one entity in relation to another.

Example Usage in an ER Model:

One-to-Many (1:M): Acustomer can place multiple orders, but each order belongs to onlyonecustomer.

Customers (1) ——— (M) Orders

Cardinality notation:

(1,1) → One-to-One

(0,M) → Zero-to-Many

(1,M) → One-to-Many

Why Other Options Are Incorrect:

Option B (Physical design) (Incorrect):Focuses onstorage and indexing, not relationships.

Option C (Attribute minimum) (Incorrect):No such formal term in database modeling.

Option D (Partition) (Incorrect):Refers todividing tables, not relationship constraints.

Thus, the correct answer isCardinality, as it definesmin/max constraints on relationships.

Binary searchis an algorithm that finds a search value byrepeatedly dividing the search space into two halves. It is commonly used inindexed searches.

Example Usage in Databases:

B-Trees and B+ Trees(used in database indexing) applybinary searchto navigate the index efficiently.

If searching for ID = 50 in asorted list of IDs, binary search:

Splits the list into two halves.

Checks the middle value.

Eliminates half of the dataset.

Repeats until the value is found.

Why Other Options Are Incorrect:

Option A (Table scan) (Incorrect):Readsevery row,much slowerthan binary search.

Option C (Index scan) (Incorrect):Uses indexes but does not necessarily apply binary search.

Option D (Fan-out) (Incorrect):Describesbranching in B-Trees, not searching.

Thus, the correct answer isBinary search, as it repeatedlysplits the indexin two.

Aprimary keyuniquely identifies each row in a table. When a primary key consists ofonly one field, it is called aSimple Primary Key.

Types of Primary Keys:

Simple Primary Key (Correct Answer):

Contains onlyone column.

Example:

sql

CREATE TABLE Students (

StudentID INT PRIMARY KEY,

Name VARCHAR(50)

);

Composite Primary Key:

Usesmultiple columnsto ensure uniqueness.

Example:

sql

CREATE TABLE Orders (

OrderID INT,

ProductID INT,

PRIMARY KEY (OrderID, ProductID)

);

Surrogate Primary Key:

A system-generatedunique identifier(e.g., UUID or AUTO_INCREMENT).

Why Other Options Are Incorrect:

Option B (Duplicate) (Incorrect):A primary keymust be unique, so itcannot be duplicate.

Option C (Numeric) (Incorrect):While primary keyscan be numeric, they can also be alphanumeric (VARCHAR).

Option D (Composite) (Incorrect):Acompositekey consists ofmultiple fields, whereas a simple key isa single field.

Thus, the correct answer isSimple, since aone-field primary keyis a simple primary key.

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.

Anindex scanis a database operation thatquickly locates table blocksusing anindexrather than scanning the entire table. It significantly improves query performance.

Example Usage:

sql

SELECT * FROM Employees WHERE EmployeeID = 105;

If EmployeeID isindexed, the database uses anindex scantoquickly find the record.

Why Other Options Are Incorrect:

Option A (Binary search) (Incorrect):A searching algorithm, but not a database operation.

Option B (Table scan) (Incorrect):Scans theentire table, which isslowerthan an index scan.

Option C (Fan-out) (Incorrect):Refers tobranching in B-Treesbut doesnot locate table blocks directly.

Thus, the correct answer isIndex scan, as it efficiently locates table blocks.

ADatabase Administrator (DBA)is responsible for the management, security, and performance of a database system. This includes controlling access to data, ensuring database integrity, optimizing performance, managing backups, and protecting the system from unauthorized access.

Option A (Incorrect):A DBA is not just a consumer of data but is primarily responsible for the database’s management.

Option B (Correct):Security is one of the key responsibilities of a DBA, including enforcing user access controls and implementing encryption and authentication mechanisms.

Option C (Incorrect):While DBAs work with data structures, it is typically the role of adata architectordatabase designerto define data formats and schema structures.

Option D (Incorrect):Developing application programs that interact with the database is typically the role ofsoftware developersordatabase programmers, not DBAs.

ATransaction ManagerensuresACID (Atomicity, Consistency, Isolation, Durability)properties in database transactions. It manages concurrent transactions, ensuring no conflicts occur and logs modifications to support recovery mechanisms.

Option A (Incorrect):Query optimization is managed by thequery processor, not the transaction manager.

Option B (Incorrect):The transaction manager is a component of the database architecture but is not composed of the entire system (query processor, storage manager, etc.).

Option C (Correct):The transaction manager logs transactions like INSERT, UPDATE, and DELETE, ensuring consistency and recoverability.

Option D (Incorrect):Thestorage manageris responsible for translating queries into filesystem commands.

Aquery processoris responsible forquery optimization and executionin a database management system (DBMS). It analyzes SQL statements, optimizes execution plans, and ensures efficient retrieval of data.

Option A (Correct):Thequery processoroptimizes queries by analyzing metadata from thesystem catalogto determine the best execution strategy.

Option B (Incorrect):Logging transactionsbefore applying changes is the responsibility of thetransaction manager.

Option C (Incorrect):Translating instructions intofile system commandsis handled by thestorage manager, not the query processor.

Option D (Incorrect):While the query processor helps retrieve results, thedatabaseengineandAPI layerare responsible for returning results to applications.

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.

Toadd a primary key constraint after table creation, we use theALTER TABLEstatement.

Example Usage:

sql

ALTER TABLE Employees

ADD CONSTRAINT PK_Employees PRIMARY KEY (EmpID);

Thisaddsa primary key to the EmpID columnafter the table was created.

Why Other Options Are Incorrect:

Option B (CREATE TABLE) (Incorrect):Used for defining constraintsduringtable creation, not after.

Option C (UPDATE) (Incorrect):Modifiesrow values, not constraints.

Option D (INSERT INTO) (Incorrect):Used toadd datato a table, not modify constraints.

Thus, the correct answer isALTER TABLE, as itmodifies table structure to add a primary key constraint.

AFull Join (FULL OUTER JOIN)selectsall records from both tables, filling in NULL values where there is no match. This ensures that no data is lost from either table.

Example Usage:

sql

SELECT Employees.Name, Departments.DepartmentName

FROM Employees

FULL OUTER JOIN Departments ON Employees.DeptID = Departments.ID;

This query retrievesall employees and all departments, even if an employeehas no assigned departmentor a departmenthas no employees.

Types of Joins:

FULL OUTER JOIN (Correct Answer)→ Includesall rows from both tables, filling missing values with NULL.

LEFT JOIN (Incorrect)→ Includesall rows from the left tableandmatching rows from the right table.

RIGHT JOIN (Incorrect)→ Includesall rows from the right tableandmatching rows from the left table.

CROSS JOIN (Incorrect)→ Produces aCartesian product(each row from one table is combined with every row from another table).

Thus, the correct answer isFULL JOIN, whichensures that all rows from both tables appear in the result.

Avalid SELECT statementin SQL follows this basic syntax:

sql

SELECT column1, column2

FROM table_name

WHERE condition;

The correct optionDfollows this syntaxcorrectly.

Why Other Options Are Incorrect:

Option A (Incorrect):SQL does not usedouble quotes(") around column/table names unless explicitly required in some databases.

Option B (Incorrect):The WHERE clausemust appear after the FROM clause.

Option C (Incorrect):ALL isnota valid keyword in standard SQL queries.

Thus,Option Dfollows the correct SQL syntax.

Anaggregate functionperforms acalculation over multiple rowsand returns asingle value. Examples includeSUM(), AVG(), MAX(), MIN(), and COUNT()in SQL.

Option A (Correct):Aggregate functions compute values over aset of rows, like summingtotal sales or averaging grades.

Option B (Incorrect):Selecting rows that appear in one table but not another is done usingset operations (EXCEPT or MINUS in SQL).

Option C (Incorrect):Eliminating columns is done using thePROJECToperation orSELECT with specific columns.

Option D (Incorrect):Combining rows from two tables refers to aJOIN operation, not aggregation.

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.