WGU C170 SQL STUDY GUIDE 2026/2027 | Most Important SQL Commands | Database Applications | Pass Guaranteed - A+ Graded

WGU C170 SQL STUDY GUIDE 2026/2027 | Most Important
SQL Commands | Database Applications | Pass Guaranteed -
A+ Graded



Section 1: Data Query Language (DQL) - SELECT Fundamentals
(Q1-18)


Q1. Consider the following table structure:

sqlCopy

CREATE TABLE employees (
emp_id INT PRIMARY KEY,
first_name VARCHAR(50),
last_name VARCHAR(50),
department VARCHAR(50),
salary DECIMAL(10,2)
);


Which query correctly retrieves only the first and last names of all employees?


A. SELECT * FROM employees WHERE first_name, last_name;


B. SELECT first_name AND last_name FROM employees;


C. SELECT first_name, last_name FROM employees; [CORRECT]


D. GET first_name, last_name FROM employees;

,Rationale: The correct syntax uses SELECT followed by comma-separated column

names and FROM to specify the table. Option A incorrectly places columns after WHERE,

B uses AND instead of a comma, and D uses invalid GET keyword.


Correct Answer: C



Q2. Given the employees table from Q1, which query retrieves all columns for all rows?


A. SELECT ALL FROM employees;


B. SELECT * FROM employees; [CORRECT]


C. SELECT EVERYTHING FROM employees;


D. SELECT columns FROM employees;


Rationale: The asterisk (*) is the ANSI SQL wildcard for all columns. Option A uses ALL

incorrectly (it modifies SELECT for duplicates, not column selection), C is not valid SQL,

and D is syntactically incorrect.

Correct Answer: B



Q3. Consider the employees table with the following data:

Table


emp_id first_name last_name department salary

, 1 John Smith Sales 5000
0



2 Jane Doe Sales 5500
0



3 Bob Johnson IT 6000
0



4 Alice Williams IT 6000
0


Which query returns only unique department names?


A. SELECT department FROM employees GROUP BY department;


B. SELECT UNIQUE department FROM employees;


C. SELECT DISTINCT department FROM employees; [CORRECT]


D. SELECT department FROM employees DISTINCT;


Rationale: DISTINCT eliminates duplicate rows and must appear immediately after

SELECT. Option A groups but doesn't necessarily return only unique values without

aggregation, B uses incorrect UNIQUE keyword, and D places DISTINCT in the wrong

position.

Correct Answer: C



Q4. Given the employees table, which query returns the first 3 rows only?

, A. SELECT * FROM employees LIMIT 3; [CORRECT]


B. SELECT * FROM employees TOP 3;


C. SELECT FIRST 3 * FROM employees;


D. SELECT * FROM employees FIRST 3;


Rationale: LIMIT is the ANSI SQL:2023 standard for restricting result rows. Option B

uses TOP which is T-SQL (SQL Server) syntax and must appear after SELECT, C and D

use invalid syntax for limiting rows.

Correct Answer: A



Q5. Which query correctly uses TOP syntax for SQL Server to return the first 5 rows from

the employees table?


A. SELECT TOP 5 * FROM employees; [CORRECT]


B. SELECT * TOP 5 FROM employees;


C. SELECT * FROM employees TOP 5;


D. SELECT FIRST 5 * FROM employees;


Rationale: In T-SQL (SQL Server), TOP must appear immediately after SELECT. Options

B, C, and D all place TOP or FIRST in incorrect positions within the query.


Correct Answer: A



Q6. Consider this query: