Free Practice Questions for WGU Data-Management-Foundations Exam

TheABS()function in SQL returns theabsolute valueof a given number, effectively measuring itsdistance from zero.

Example Usage:

sql

SELECT ABS(-50), ABS(50);

Result:

50 | 50

This function ensures that numbers arealways positive, regardless of their original sign.

Why Other Options Are Incorrect:

Option A (CONCAT) (Incorrect):Used tocombine strings(not numbers).

Option B (LOWER) (Incorrect):Converts text tolowercase, not numerical operations.

Option C (FROM) (Incorrect):Part of SELECT FROM queries,not a function.

Thus, the correct choice isABS(), which computes the absolute value of a number.

TheUNIONkeyword in SQL is used tocombine the resultsof two or more SELECT queries into asingle result setwhile 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 insome database systems for data merging).

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

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

Asimple primary keyconsists ofonly one columnthat uniquely identifies each row in a table.

Example Usage:

sql

CREATE TABLE Students (

StudentID INT PRIMARY KEY,

Name VARCHAR(50)

);

StudentIDis asimple primary keybecause it consists of only one field.

Why Other Options Are Incorrect:

Option B (Partition) (Incorrect):Refers topartitioned tables, which divide data for performance reasons butare not related to primary keys.

Option C (Stable) (Incorrect):This is not a recognized term in database keys.

Option D (Meaningless) (Incorrect):Primary keys are oftenmeaningless (e.g., auto-incremented IDs), but this isnot a term used to describe their structure.

Thus, the correct answer isSimple, as asingle-field primary keyis referred to as asimple primary key.

Aggregate functionsperform calculationson a set of values and return asingle result.MAX()is one such function, returning thelargest value in a column.

Common Aggregate Functions:

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Example Usage:

sql

SELECT MAX(Salary) FROM Employees;

Retrieves thehighest salaryin the Employees table.

Why Other Options Are Incorrect:

Option B (TRIM) (Incorrect):Removes spaces from strings butis not an aggregate function.

Option C (ABS) (Incorrect):Returns theabsolute value of a numberbut doesnot aggregate multiple rows.

Option D (DESC) (Incorrect):Used in ORDER BY forsorting in descending order,not for aggregation.

Thus, the correct answer isMAX(), as it is atrue aggregate function.

Avalid SELECT statementin SQL follows this basic syntax:

sql

SELECT column1, column2

FROM table_name

WHERE condition;

The correct optionDfollows this syntaxcorrectly.

Why Other Options Are Incorrect:

Option A (Incorrect):SQL does not usedouble quotes(") around column/table names unless explicitly required in some databases.

Option B (Incorrect):The WHERE clausemust appear after the FROM clause.

Option C (Incorrect):ALL isnota valid keyword in standard SQL queries.

Thus,Option Dfollows the correct SQL syntax.

TheWHEREclause is used inSQL SELECT statementstolimitthe number of rows that match a specific condition. It helps filter data based on given criteria before retrieving the results.

Example Usage:

sql

SELECT *

FROM Employees

WHERE Salary > 50000;

This querylimitsthe result set to employees whose salary isgreater than 50,000.

Why Other Options Are Incorrect:

Option A (FROM) (Incorrect):Specifies the table from which data is retrieved butdoes not limit results.

Option B (DROP) (Incorrect):Used fordeleting tables, databases, or views, not filtering rows.

Option C (INTO) (Incorrect):Used in statements like INSERT INTO or SELECT INTO, whichdo not filter results.

Thus,WHERE is the correct keywordfor applying alimiter in a SELECT statement.

TheMERGEstatement, also known asUPSERT, combinesINSERT, UPDATE, and DELETEoperations into asingle statementbased on a given condition. It is commonly used indata warehouses and large-scale databases.

Example Usage:

sql

MERGE INTO Employees AS Target

USING NewEmployees AS Source

ON Target.ID = Source.ID

WHEN MATCHED THEN

UPDATE SET Target.Salary = Source.Salary

WHEN NOT MATCHED THEN

INSERT (ID, Name, Salary) VALUES (Source.ID, Source.Name, Source.Salary);

If a match is found, the UPDATE clause modifies the existing record.

If no match is found, the INSERT clause adds a new record.

Why Other Options Are Incorrect:

Option A (INTO) (Incorrect):Used in INSERT INTO, butdoes not combine operations.

Option B (JOIN) (Incorrect):Used to combine rows from multiple tables, butnot for merging data.

Option D (DROP) (Incorrect):Deletes database objects liketables, views, and indexes, butdoes not merge data.

Thus, the correct answer isMERGE, as itcombines inserts, updates, and deletes into a single operation.

Cardinalitydefines theminimum and maximum number of occurrencesof one entity in relation to another.

Example Usage in an ER Model:

One-to-Many (1:M): Acustomer can place multiple orders, but each order belongs to onlyonecustomer.

Customers (1) ——— (M) Orders

Cardinality notation:

(1,1) → One-to-One

(0,M) → Zero-to-Many

(1,M) → One-to-Many

Why Other Options Are Incorrect:

Option B (Physical design) (Incorrect):Focuses onstorage and indexing, not relationships.

Option C (Attribute minimum) (Incorrect):No such formal term in database modeling.

Option D (Partition) (Incorrect):Refers todividing tables, not relationship constraints.

Thus, the correct answer isCardinality, as it definesmin/max constraints on relationships.

Thecorrect syntaxfor inserting a new row into a table follows this structure:

Standard SQL INSERT Syntax:

sql

INSERT INTO TableName (Column1, Column2, ...)

VALUES (Value1, Value2, ...);

For this scenario:

sql

INSERT INTO Employee (Name) VALUES ('John Doe');

Why Other Options Are Incorrect:

Option A (Incorrect):Uses incorrect syntax { ... }, which isnot valid SQL syntax.

Option C (Incorrect):Does not specify the column name, whichcauses an error.

Option D (Incorrect):Misses theINTOkeyword, which is required in standard SQL.

Thus, the correct syntax isOption B, ensuring aproperly formatted insert statement.