WGU Data-Management-Foundations Dumps PDF Free Download

QUESTION: 9

Which keyword can be used as a clause in an ALTER TABLE statement?

DELETE
CHANGE
STOP
AGGREGATE

Answer(s): B

Explanation:

The ALTER TABLE statement is used to modify an existing database table structure. One common clause is CHANGE, 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 remove rows, not alter table structure.

Option B (Correct): CHANGE is a valid clause for 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.

Reference:

SQL ALTER TABLE syntax in SE 3050 zyBooks.

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QUESTION: 10

How many bytes of storage does a BIGINT data type hold in MySQL?

1 byte
3 bytes
4 bytes
8 bytes

Answer(s): D

Explanation:

In MySQL, the BIGINT data type is a 64-bit integer that requires 8 bytes (64 bits) of storage. It is used to store large numerical values beyond the range of INT (4 bytes).

Option A (Incorrect): 1 byte corresponds to TINYINT, which can store values from -128 to 127.

Option B (Incorrect): 3 bytes is not a standard integer storage size in MySQL.

Option C (Incorrect): 4 bytes corresponds to INT, which has a range of -2,147,483,648 to 2,147,483,647.

Option D (Correct): BIGINT takes 8 bytes and supports a massive range of numbers from -2^63 to 2^63 -1.

Reference:

MySQL data types and storage requirements.

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QUESTION: 11

Which action does the % operator accomplish in MySQL?

Raises a numeric value to the power of another
Compares two numeric values for equality
Divides two numeric values and returns the remainder
Subtracts a numeric value from another

Answer(s): C

Explanation:

The % operator in MySQL is known as the modulus operator. It returns the remainder of a division operation between two numbers.

Example:

sql

SELECT 10 % 3; -- Output: 1 (10 divided by 3 gives remainder 1)

Option A (Incorrect): Raising a number to a power is done using the POW() function or ^ in some SQL dialects.

Option B (Incorrect): The = operator is used for equality comparisons, not %.

Option C (Correct): The modulus operator (%) finds the remainder when one number is divided by another.

Option D (Incorrect): Subtraction is performed using the - operator.

Reference:

MySQL arithmetic operators.

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QUESTION: 12

Which clause from a SELECT statement immediately accompanies the SELECT clause in MySQL?

FROM
VALUE
WHERE
TABLE

Answer(s): A

Explanation:

In SQL syntax, the FROM clause is the first clause that follows SELECT. It specifies the table(s) from which the data will be retrieved.

Example:

sql

SELECT name, salary FROM Employees;

Option A (Correct): The FROM clause immediately follows the SELECT clause in MySQL.

Option B (Incorrect): VALUE is not a valid clause in MySQL SELECT statements.

Option C (Incorrect): WHERE is used to filter records after specifying the table in FROM.

Option D (Incorrect): TABLE is not a valid clause following SELECT in SQL.

Reference:

MySQL SELECT statement structure.

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QUESTION: 13

Which characteristic is true for non-relational databases?

They are optimized for big data.
They support the SQL query language.
They are ideal for databases that require an accurate record of transactions.
They store data in tables, columns, and rows, similar to a spreadsheet.

Answer(s): A

Explanation:

Non-relational databases (also called NoSQL databases) are designed for handling big data and unstructured data efficiently. They are optimized for horizontal scaling, making them ideal for large- scale distributed systems.

Option A (Correct): Non-relational databases are optimized for big data, handling massive volumes of data across distributed architectures.

Option B (Incorrect): NoSQL databases do not use SQL as their primary query language. They often use JSON-based queries (e.g., MongoDB).

Option C (Incorrect): Transaction-heavy applications require ACID compliance, which relational databases (SQL) handle better than NoSQL databases.

Option D (Incorrect): NoSQL databases use document, key-value, graph, or column-family storage models, not tables, columns, and rows like relational databases.

Reference:

Characteristics of NoSQL databases.

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QUESTION: 14

Which clause is used to specify the join columns when performing a join in MySQL?

AS
JOIN
ON
AND

Answer(s): C

Explanation:

When performing a JOIN operation in MySQL, the ON clause specifies the joining 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 for aliasing tables and columns, not for specifying join conditions.

Option B (Incorrect): JOIN defines the type of join (INNER JOIN, LEFT JOIN, etc.), but does not specify the columns.

Option C (Correct): The ON clause is used to specify the join condition between two tables.

Option D (Incorrect): AND is used in filtering conditions, not for joining tables.

Reference:

MySQL JOIN operations.

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QUESTION: 15

Which keyword can be used to combine two results into one table?

UNION
MERGE
INTEGRATE
CONSOLIDATE

Answer(s): A

Explanation:

The UNION keyword in SQL is used to combine the results of two or more SELECT queries into a single result set while removing duplicate rows.

Example:

sql

SELECT Name FROM Employees

UNION

SELECT Name FROM Managers;

Option A (Correct): UNION combines results from multiple queries into one set, removing duplicates.

Option B (Incorrect): MERGE is not a valid SQL keyword for combining result sets (it is used in some database systems for data merging).

Option C (Incorrect): INTEGRATE is not a SQL keyword.

Option D (Incorrect): CONSOLIDATE is not an SQL keyword.

Reference:

SQL UNION and set operations.

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QUESTION: 16

Which type of join is demonstrated by the following query?

sql

SELECT *

FROM Make, Model

WHERE Make.ModelID = Model.ID;

NON-EQUIJOIN
SELF JOIN
EQUIJOIN
CROSS JOIN

Answer(s): C

Explanation:

This query performs a join operation where records from the Make table and Model table are combined based on the condition Make.ModelID = Model.ID. This condition tests for equality, which is the definition of an EQUIJOIN.

Types of Joins in SQL:

EQUIJOIN (Correct Answer):

Uses an equality operator (=) to match rows between tables.

Equivalent to an INNER JOIN ON condition.

Example:

sql

SELECT *

FROM Employees

JOIN Departments ON Employees.DeptID = Departments.ID;

NON-EQUIJOIN (Incorrect):

Uses comparison operators other than = (e.g., <, >, BETWEEN).

Example:

sql

SELECT *

FROM Employees e

JOIN Salaries s ON e.Salary > s.MedianSalary;

SELF JOIN (Incorrect):

A table is joined with itself using table aliases.

Example:

sql

SELECT e1.Name, e2.Name AS Manager

FROM Employees e1

JOIN Employees e2 ON e1.ManagerID = e2.ID;

CROSS JOIN (Incorrect):

Produces Cartesian product (each row from Table A combines with every row from Table B).

Example:

sql

SELECT *

FROM Employees

CROSS JOIN Departments;

Thus, since our given query uses an equality condition (=) to join two tables, it is an EQUIJOIN.

Reference:

SQL Joins in relational databases.

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WGU Data Management - Foundations Data-Management-Foundations Dumps in PDF

Free WGU Data-Management-Foundations Real Questions (page: 9)

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