WGU Data-Management-Foundations Exam With Confidence Using Practice Dumps

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.

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.

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.