D427 Wgu Database Management Applications Exam – Latest Update - (Complete Solution)

D427 WGU DATABASE MANAGEMENT APPLICATIONS EXAM –
LATEST UPDATE - (COMPLETE SOLUTION)
Question 1

Which statement best describes a relational database?

A. A collection of unrelated text files
B. A database that organizes data into tables containing rows and columns
C. A database that stores only images
D. A system that cannot establish relationships between data

Correct Answer: B. A database that organizes data into tables containing
rows and columns

Rationale: A relational database organizes structured data into tables. Rows
represent individual records, while columns represent attributes of those
records. Relationships between tables are established using keys.



Question 2

What is a primary key?

A. A column that may contain duplicate values
B. A column or combination of columns that uniquely identifies each row
C. A column used only for displaying data
D. A foreign table

Correct Answer: B. A column or combination of columns that uniquely
identifies each row

Rationale: A primary key provides a unique identifier for each record in a
table. It must contain unique values and cannot contain NULL values.



Question 3

Which SQL statement is used to retrieve data from a database?

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,A. INSERT
B. UPDATE
C. SELECT
D. DELETE

Correct Answer: C. SELECT

Rationale: SELECT retrieves data from one or more tables. It can be
combined with clauses such as WHERE, ORDER BY, GROUP BY, and HAVING to
control which data is returned and how it is presented.



Question 4

Which SQL statement adds a new row to a table?

A. INSERT
B. CREATE
C. ALTER
D. UPDATE

Correct Answer: A. INSERT

Rationale: INSERT is a data manipulation language statement used to add
new records to a table. UPDATE modifies existing records, while CREATE is a
data definition language statement used to create database objects.



Question 5

Which SQL statement modifies existing records?

A. SELECT
B. UPDATE
C. CREATE
D. DROP

Correct Answer: B. UPDATE


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,Rationale: UPDATE changes values in existing rows. A WHERE clause should
normally be used to identify the intended rows; otherwise, the statement can
modify every row in the table.



Question 6

Which SQL statement removes rows from a table?

A. DELETE
B. REMOVE
C. DROP ROW
D. CLEAR

Correct Answer: A. DELETE

Rationale: DELETE removes rows from a table. When used with a WHERE
clause, only matching rows are removed. Without a WHERE clause, all rows in
the table can be deleted.



Question 7

What does a foreign key accomplish?

A. It uniquely identifies every database
B. It establishes a relationship between tables
C. It automatically encrypts a table
D. It prevents all duplicate data

Correct Answer: B. It establishes a relationship between tables

Rationale: A foreign key contains values that reference a candidate or
primary key in another table. It helps enforce referential integrity and
represents relationships between related entities.



Question 8

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, Which constraint prevents a column from containing NULL values?

A. UNIQUE
B. DEFAULT
C. NOT NULL
D. CHECK

Correct Answer: C. NOT NULL

Rationale: The NOT NULL constraint requires a value to be supplied for the
column. This is useful when an attribute must always have a known value.



Question 9

Which constraint ensures that values in a column are not duplicated?

A. UNIQUE
B. NULL
C. DEFAULT
D. CHECK

Correct Answer: A. UNIQUE

Rationale: The UNIQUE constraint prevents duplicate values within the
constrained column or combination of columns. Unlike a primary key, a
UNIQUE constraint may have different NULL behavior depending on the
database management system.



Question 10

What is the purpose of a CHECK constraint?

A. To define a condition that column values must satisfy
B. To create a foreign key automatically
C. To sort query results
D. To delete duplicate rows


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