WGU DATA MANAGEMENT FOUNDATIONS
D426 EXAMINATION TEST 2026 SOLVED
QUESTIONS 100% CORRECT
◉ determinant. Answer: A determinant is an attribute (or a set of
attributes) in a database that uniquely determines the value of another
attribute. It is the "left side" of a functional dependency.
Example 1: In the functional dependency StudentID → StudentName,
the determinant is StudentID because it uniquely identifies the
StudentName.Example 2: In ISBN → BookTitle, the determinant is
ISBN, as it uniquely determines the BookTitle.
4o
◉ Candidate Key. Answer: A candidate key is a minimal set of attributes
in a database table that can uniquely identify each row in that table. Each
table can have multiple candidate keys, but one is selected as the
primary key.
Example 1: In a table of students, StudentID and Email might both
uniquely identify a student. Both are candidate keys.Example 2: In an
employee table, EmployeeID and SocialSecurityNumber (SSN) could be
candidate keys if they uniquely identify each employee
,◉ DDL. Answer: DDL (Data Definition Language) refers to SQL
commands used to define or modify the structure of database objects
such as tables, schemas, and indexes. Common DDL commands include
CREATE, ALTER, DROP, and TRUNCATE.
◉ DCL. Answer: (Data Control Language) refers to SQL commands that
control access to data within a database by managing user permissions
and rights. Common DCL commands include GRANT (to give access)
and REVOKE (to remove access).
◉ DDL. Answer: (Data Definition Language) refers to SQL commands
used to define and modify the structure of database objects like tables,
schemas, and indexes. Common DDL commands include CREATE,
ALTER, DROP, and TRUNCATE.
◉ A Materialized View. Answer: is a database object that stores the
results of a query physically on disk, allowing faster access to
precomputed query results. Unlike regular views, materialized views are
not updated dynamically; they need to be refreshed periodically to
reflect changes in the underlying data.
◉ A Virtual View. Answer: (or simply a View) is a database object that
presents data from one or more tables in a specific way without storing
the data itself. It is essentially a stored query that generates results
dynamically when accessed.
,◉ Metadata. Answer: refers to data that describes other data. It provides
information about the structure, attributes, and context of data, helping
to understand and manage the actual data more effectively.
◉ A tuple. Answer: is a single, ordered set of values or elements in a
database, often represented as a row in a table. Each value in a tuple
corresponds to an attribute (or column) of the table.
◉ Hit ratio. Answer: is a performance metric used to measure the
effectiveness of a cache in storing frequently accessed data. It is the
percentage of cache accesses that result in a hit (when the requested data
is found in the cache) compared to the total number of cache accesses.
Example 1: If a cache is accessed 100 times, and 80 of those accesses
find the data in the cache, the hit ratio is 80%.Example 2: A higher hit
ratio indicates better cache performance, reducing the need to retrieve
data from slower storage.
Hit ratio is critical for optimizing data retrieval speeds and system
efficiency.
◉ A table scan. Answer: is a process in which the database management
system (DBMS) reads all the rows in a table to find the data that meets a
query's conditions. This is usually less efficient than using an index, as it
requires checking every row, which can be slow for large tables.
Example 1: If a query requests data without using an index, the DBMS
will perform a table scan, examining each row one by one.Example 2:
For a table with millions of rows, a table scan can lead to slow query
performance compared to an indexed search.
, 4o mini
◉ An index scan. Answer: is a process where the database management
system (DBMS) uses an index to quickly locate rows in a table that
match a query's conditions. It is more efficient than a table scan because
it narrows down the search to a specific range of rows, rather than
checking every row in the table.
Example 1: When querying a column with an index, the DBMS uses the
index to quickly identify relevant rows instead of scanning the entire
table.Example 2: For a table with an index on a "CustomerID" column,
an index scan can rapidly locate all rows with a specific customer ID,
improving query performance.
◉ Binary search. Answer: is an efficient algorithm for finding an
element in a sorted list by repeatedly dividing the search interval in half.
If the value of the search key is less than the item in the middle of the
list, the search continues in the lower half, otherwise, it continues in the
upper half. This process is repeated until the value is found or the search
interval is empty.
Example 1: Searching for a number in a sorted list of integers: 1, 3, 5, 7,
9. Starting in the middle (5), if the target is 7, the algorithm moves to the
right half (7, 9) and finds the target.Example 2: In a phonebook with
sorted names, binary search can quickly locate a specific name by
comparing it to the middle entry, then narrowing the search to the
appropriate half of the list.
D426 EXAMINATION TEST 2026 SOLVED
QUESTIONS 100% CORRECT
◉ determinant. Answer: A determinant is an attribute (or a set of
attributes) in a database that uniquely determines the value of another
attribute. It is the "left side" of a functional dependency.
Example 1: In the functional dependency StudentID → StudentName,
the determinant is StudentID because it uniquely identifies the
StudentName.Example 2: In ISBN → BookTitle, the determinant is
ISBN, as it uniquely determines the BookTitle.
4o
◉ Candidate Key. Answer: A candidate key is a minimal set of attributes
in a database table that can uniquely identify each row in that table. Each
table can have multiple candidate keys, but one is selected as the
primary key.
Example 1: In a table of students, StudentID and Email might both
uniquely identify a student. Both are candidate keys.Example 2: In an
employee table, EmployeeID and SocialSecurityNumber (SSN) could be
candidate keys if they uniquely identify each employee
,◉ DDL. Answer: DDL (Data Definition Language) refers to SQL
commands used to define or modify the structure of database objects
such as tables, schemas, and indexes. Common DDL commands include
CREATE, ALTER, DROP, and TRUNCATE.
◉ DCL. Answer: (Data Control Language) refers to SQL commands that
control access to data within a database by managing user permissions
and rights. Common DCL commands include GRANT (to give access)
and REVOKE (to remove access).
◉ DDL. Answer: (Data Definition Language) refers to SQL commands
used to define and modify the structure of database objects like tables,
schemas, and indexes. Common DDL commands include CREATE,
ALTER, DROP, and TRUNCATE.
◉ A Materialized View. Answer: is a database object that stores the
results of a query physically on disk, allowing faster access to
precomputed query results. Unlike regular views, materialized views are
not updated dynamically; they need to be refreshed periodically to
reflect changes in the underlying data.
◉ A Virtual View. Answer: (or simply a View) is a database object that
presents data from one or more tables in a specific way without storing
the data itself. It is essentially a stored query that generates results
dynamically when accessed.
,◉ Metadata. Answer: refers to data that describes other data. It provides
information about the structure, attributes, and context of data, helping
to understand and manage the actual data more effectively.
◉ A tuple. Answer: is a single, ordered set of values or elements in a
database, often represented as a row in a table. Each value in a tuple
corresponds to an attribute (or column) of the table.
◉ Hit ratio. Answer: is a performance metric used to measure the
effectiveness of a cache in storing frequently accessed data. It is the
percentage of cache accesses that result in a hit (when the requested data
is found in the cache) compared to the total number of cache accesses.
Example 1: If a cache is accessed 100 times, and 80 of those accesses
find the data in the cache, the hit ratio is 80%.Example 2: A higher hit
ratio indicates better cache performance, reducing the need to retrieve
data from slower storage.
Hit ratio is critical for optimizing data retrieval speeds and system
efficiency.
◉ A table scan. Answer: is a process in which the database management
system (DBMS) reads all the rows in a table to find the data that meets a
query's conditions. This is usually less efficient than using an index, as it
requires checking every row, which can be slow for large tables.
Example 1: If a query requests data without using an index, the DBMS
will perform a table scan, examining each row one by one.Example 2:
For a table with millions of rows, a table scan can lead to slow query
performance compared to an indexed search.
, 4o mini
◉ An index scan. Answer: is a process where the database management
system (DBMS) uses an index to quickly locate rows in a table that
match a query's conditions. It is more efficient than a table scan because
it narrows down the search to a specific range of rows, rather than
checking every row in the table.
Example 1: When querying a column with an index, the DBMS uses the
index to quickly identify relevant rows instead of scanning the entire
table.Example 2: For a table with an index on a "CustomerID" column,
an index scan can rapidly locate all rows with a specific customer ID,
improving query performance.
◉ Binary search. Answer: is an efficient algorithm for finding an
element in a sorted list by repeatedly dividing the search interval in half.
If the value of the search key is less than the item in the middle of the
list, the search continues in the lower half, otherwise, it continues in the
upper half. This process is repeated until the value is found or the search
interval is empty.
Example 1: Searching for a number in a sorted list of integers: 1, 3, 5, 7,
9. Starting in the middle (5), if the target is 7, the algorithm moves to the
right half (7, 9) and finds the target.Example 2: In a phonebook with
sorted names, binary search can quickly locate a specific name by
comparing it to the middle entry, then narrowing the search to the
appropriate half of the list.
