WGU D465 Data Applications Objective Assessment
Questions and Answers| Updated| Pass Guaranteed
1. Which statement best distinguishes data from information?
A. Information is data that has been processed and given context so it is
meaningful.
B. Data is always more useful than information.
C. Information is raw, unorganized facts, while data is analyzed results.
D. Data and information are identical terms in database design.
Answer: A. Information is data that has been processed and given
context so it is meaningful.
Rationale: Raw facts are data. When they are organized, processed,
and placed in context, they become information that supports decisions.
2. What is the primary purpose of a primary key in a relational table?
A. To link a table to a different database
B. To uniquely identify each row in the table
C. To allow duplicate values in a column
D. To sort the rows alphabetically
Answer: B. To uniquely identify each row in the table
Rationale: A primary key must be unique and not null, so every row can
be identified unambiguously.
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,3. A foreign key in one table is best described as:
A. A key used only to speed up searches
B. A column that must contain unique values in its own table
C. A column that references the primary key of another table
D. A column that stores encrypted data
Answer: C. A column that references the primary key of another table
Rationale: Foreign keys create relationships between tables and
enforce referential integrity by pointing to a primary (or unique) key in a
parent table.
4. Which SQL statement retrieves data from a table?
A. ALTER
B. UPDATE
C. INSERT
D. SELECT
Answer: D. SELECT
Rationale: SELECT is the query command used to read rows and
columns. INSERT adds rows, UPDATE changes rows, and ALTER
changes table structure.
5. Which SQL command creates a new table?
A. CREATE TABLE
B. MAKE TABLE
C. INSERT TABLE
D. NEW TABLE
Answer: A. CREATE TABLE
Rationale: CREATE TABLE is a Data Definition Language (DDL)
statement that defines a new table and its columns.
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,6. Which of the following is a Data Manipulation Language (DML)
command?
A. CREATE
B. INSERT
C. GRANT
D. DROP
Answer: B. INSERT
Rationale: DML commands (SELECT, INSERT, UPDATE, DELETE)
work with the data in tables. CREATE and DROP are DDL; GRANT is
DCL.
7. What is the key difference between WHERE and HAVING?
A. They are interchangeable in all queries.
B. HAVING can only be used with INSERT statements.
C. WHERE filters rows before grouping; HAVING filters groups after
aggregation.
D. WHERE filters groups; HAVING filters individual rows.
Answer: C. WHERE filters rows before grouping; HAVING filters groups
after aggregation.
Rationale: WHERE is applied to individual rows before GROUP BY.
HAVING is applied to the grouped results, so it can use aggregate
functions such as SUM or COUNT.
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, 8. What does the GROUP BY clause do?
A. Joins two tables together
B. Removes all NULL values from the table
C. Sorts the result set in descending order
D. Combines rows with the same values in specified columns so
aggregates can be computed per group
Answer: D. Combines rows with the same values in specified columns
so aggregates can be computed per group
Rationale: GROUP BY collapses rows sharing the same values into
groups, and aggregate functions then calculate a value for each group.
9. Which join returns only the rows that have matching values in both
tables?
A. INNER JOIN
B. LEFT OUTER JOIN
C. FULL OUTER JOIN
D. CROSS JOIN
Answer: A. INNER JOIN
Rationale: An INNER JOIN returns only the intersecting rows where the
join condition is satisfied in both tables.
10. Which join returns all rows from the left table and matching rows
from the right table, with NULLs where there is no match?
A. INNER JOIN
B. LEFT OUTER JOIN
C. SELF JOIN
D. RIGHT OUTER JOIN
Answer: B. LEFT OUTER JOIN
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Questions and Answers| Updated| Pass Guaranteed
1. Which statement best distinguishes data from information?
A. Information is data that has been processed and given context so it is
meaningful.
B. Data is always more useful than information.
C. Information is raw, unorganized facts, while data is analyzed results.
D. Data and information are identical terms in database design.
Answer: A. Information is data that has been processed and given
context so it is meaningful.
Rationale: Raw facts are data. When they are organized, processed,
and placed in context, they become information that supports decisions.
2. What is the primary purpose of a primary key in a relational table?
A. To link a table to a different database
B. To uniquely identify each row in the table
C. To allow duplicate values in a column
D. To sort the rows alphabetically
Answer: B. To uniquely identify each row in the table
Rationale: A primary key must be unique and not null, so every row can
be identified unambiguously.
Page 1
,3. A foreign key in one table is best described as:
A. A key used only to speed up searches
B. A column that must contain unique values in its own table
C. A column that references the primary key of another table
D. A column that stores encrypted data
Answer: C. A column that references the primary key of another table
Rationale: Foreign keys create relationships between tables and
enforce referential integrity by pointing to a primary (or unique) key in a
parent table.
4. Which SQL statement retrieves data from a table?
A. ALTER
B. UPDATE
C. INSERT
D. SELECT
Answer: D. SELECT
Rationale: SELECT is the query command used to read rows and
columns. INSERT adds rows, UPDATE changes rows, and ALTER
changes table structure.
5. Which SQL command creates a new table?
A. CREATE TABLE
B. MAKE TABLE
C. INSERT TABLE
D. NEW TABLE
Answer: A. CREATE TABLE
Rationale: CREATE TABLE is a Data Definition Language (DDL)
statement that defines a new table and its columns.
Page 2
,6. Which of the following is a Data Manipulation Language (DML)
command?
A. CREATE
B. INSERT
C. GRANT
D. DROP
Answer: B. INSERT
Rationale: DML commands (SELECT, INSERT, UPDATE, DELETE)
work with the data in tables. CREATE and DROP are DDL; GRANT is
DCL.
7. What is the key difference between WHERE and HAVING?
A. They are interchangeable in all queries.
B. HAVING can only be used with INSERT statements.
C. WHERE filters rows before grouping; HAVING filters groups after
aggregation.
D. WHERE filters groups; HAVING filters individual rows.
Answer: C. WHERE filters rows before grouping; HAVING filters groups
after aggregation.
Rationale: WHERE is applied to individual rows before GROUP BY.
HAVING is applied to the grouped results, so it can use aggregate
functions such as SUM or COUNT.
Page 3
, 8. What does the GROUP BY clause do?
A. Joins two tables together
B. Removes all NULL values from the table
C. Sorts the result set in descending order
D. Combines rows with the same values in specified columns so
aggregates can be computed per group
Answer: D. Combines rows with the same values in specified columns
so aggregates can be computed per group
Rationale: GROUP BY collapses rows sharing the same values into
groups, and aggregate functions then calculate a value for each group.
9. Which join returns only the rows that have matching values in both
tables?
A. INNER JOIN
B. LEFT OUTER JOIN
C. FULL OUTER JOIN
D. CROSS JOIN
Answer: A. INNER JOIN
Rationale: An INNER JOIN returns only the intersecting rows where the
join condition is satisfied in both tables.
10. Which join returns all rows from the left table and matching rows
from the right table, with NULLs where there is no match?
A. INNER JOIN
B. LEFT OUTER JOIN
C. SELF JOIN
D. RIGHT OUTER JOIN
Answer: B. LEFT OUTER JOIN
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