SQL Learning Quizzes: Test Your Database Management Skills

Question 1

Which of the following is NOT a recognized data type in SQL?

Accepted Answer

Array

Answer

Integer

Answer

String

Answer

Boolean

Question 2

Which of the following is not a recognized data type in SQL?

Accepted Answer

Array

Answer

Integer

Answer

Char

Answer

Boolean

Question 3

Which SQL syntax correctly retrieves all rows from a table named 'students'?

Accepted Answer

SELECT * FROM students

Answer

SELECT students.* FROM students

Answer

SELECT id, name FROM students

Answer

SELECT * FROM students WHERE id = 1

Question 4

Which SQL statement creates a new table called 'Customers' with columns 'id' (integer) and 'name' (string with a maximum length of 255 characters)?

Accepted Answer

CREATE TABLE Customers (id INT, name VARCHAR(255))

Answer

SELECT * FROM Customers

Answer

INSERT INTO Customers (id, name) VALUES (1, 'John Doe')

Answer

DROP TABLE Customers

Question 5

Which SQL command retrieves data from a database?

Accepted Answer

SELECT

Answer

DELETE

Answer

ALTER

Answer

UPDATE

Question 6

What does the 'WHERE' clause accomplish in an SQL query?

Accepted Answer

Filters results based on specified conditions

Answer

Sorts the results in ascending or descending order

Answer

Groups the results by specified columns

Question 7

Which data type in SQL should you use to represent dates?

Accepted Answer

DATE

Answer

INTEGER

Answer

VARCHAR

Answer

BOOLEAN

Question 8

What is the primary purpose of the 'JOIN' statement in SQL?

Accepted Answer

Combines data from multiple related tables

Answer

Updates data in a table

Answer

Deletes data from a table

Answer

Creates a new table

Question 9

Which SQL command modifies data already present in a database?

Accepted Answer

UPDATE

Answer

SELECT

Answer

INSERT

Answer

DELETE

Question 10

How do a primary key and a foreign key differ in SQL?

Accepted Answer

A primary key uniquely identifies a row in a table, while a foreign key references a primary key in another table.

Answer

A foreign key is unique, while a primary key is not.

Question 11

Which SQL function is used to determine the maximum value in a set of data?

Accepted Answer

MAX()

Answer

COUNT()

Answer

MIN()

Answer

AVG()

Question 12

What is the purpose of the 'GROUP BY' clause in an SQL query?

Accepted Answer

Groups the results by one or more specified columns

Answer

Sorts the results in ascending or descending order

Answer

Filters the results based on specified conditions

Question 13

Which SQL command creates a new database?

Accepted Answer

CREATE DATABASE

Answer

SELECT *

Answer

CREATE TABLE

Answer

INSERT INTO

Question 14

What is the main benefit of using an index in an SQL database?

Accepted Answer

Enhances the speed of data retrieval

Answer

Enforces data integrity

Answer

Prevents duplicate data entries

Answer

Stores data in a compressed format

Question 15

Which of the following is the correct syntax to create a new SQL table named 'customers' with columns 'id', 'name', and 'email', with 'id' as the primary key?

Accepted Answer

CREATE TABLE customers (id INT PRIMARY KEY, name VARCHAR(255), email VARCHAR(255))

Answer

CREATE TABLE customers (id INT, name VARCHAR, email VARCHAR)

Answer

CREATE TABLE customers (id VARCHAR, name VARCHAR, email VARCHAR)

Question 16

Which SQL statement is used to retrieve all rows and specific columns from the 'orders' table, such as 'order_id', 'product_id', and 'quantity'?

Accepted Answer

SELECT order_id, product_id, quantity FROM orders

Answer

FETCH orders

Answer

GET orders

Answer

SELECT ALL FROM orders

Question 17

Which of the following operators is used to compare two values in SQL, checking if they are not equal?

Accepted Answer

<>

Answer

+

Answer

*

Answer

&

Question 18

How would you modify the 'orders' table to add a new column named 'total_amount' and set its default value to 0?

Accepted Answer

ALTER TABLE orders ADD COLUMN total_amount DECIMAL(10,2) DEFAULT 0

Answer

INSERT INTO orders (total_amount) VALUES (0)

Answer

UPDATE orders SET total_amount = 0

Question 19

How would you join two tables, 'customers' and 'orders', on the 'customer_id' column and only include rows where the 'order_status' column in the 'orders' table is 'shipped'?

Accepted Answer

SELECT * FROM customers INNER JOIN orders ON customers.customer_id = orders.customer_id WHERE orders.order_status = 'shipped'

Answer

SELECT * FROM customers, orders WHERE customers.customer_id = orders.customer_id

Answer

JOIN customers WITH orders ON customers.customer_id = orders.customer_id

Question 20

Which SQL command is used to delete all rows from the 'products' table where the 'quantity_on_hand' column is less than 10?

Accepted Answer

DELETE FROM products WHERE quantity_on_hand < 10

Answer

DROP TABLE products

Answer

REMOVE FROM products

Answer

TRUNCATE TABLE products

Question 21

How would you create a view named 'top_customers' that shows the top 10 customers by total sales, in descending order?

Accepted Answer

CREATE VIEW top_customers AS SELECT customer_id, SUM(total_amount) AS total_sales FROM orders GROUP BY customer_id ORDER BY total_sales DESC LIMIT 10

Answer

SELECT customer_id, SUM(total_amount) FROM orders GROUP BY customer_id ORDER BY total_sales DESC LIMIT 10

Question 22

Which SQL command retrieves data from a table?

Accepted Answer

SELECT

Answer

INSERT

Answer

UPDATE

Answer

DELETE

Question 23

What's the role of the WHERE clause in SQL?

Accepted Answer

Filters query results based on a specified condition.

Answer

Sorts query results.

Answer

Groups query results.

Question 24

What's the distinction between an INNER JOIN and an OUTER JOIN in SQL?

Accepted Answer

An INNER JOIN retrieves matching rows from both tables, while an OUTER JOIN retrieves all rows from one table and matching rows from the other.

Answer

An INNER JOIN retrieves all rows from both tables, while an OUTER JOIN retrieves only matching rows.

Question 25

Which SQL function calculates the average value of a column?

Accepted Answer

AVG()

Answer

MAX()

Answer

COUNT()

Answer

SUM()

Question 26

What's the purpose of an index in SQL?

Accepted Answer

Expedite data retrieval operations.

Answer

Create data backups.

Answer

Restrict unauthorized data access.

Answer

Maintain data integrity.

Question 27

Which option is a type of database constraint?

Accepted Answer

Primary key

Answer

View

Answer

Trigger

Answer

Index

Question 28

What's the purpose of a transaction in SQL?

Accepted Answer

Ensures that a series of database operations are executed atomically.

Answer

Creates a database backup.

Answer

Grants database access to specific users.

Question 29

Which type of SQL injection attack is known as a Union-based attack?

Accepted Answer

Union-based attack

Answer

Phishing attack

Answer

Brute force attack

Answer

Cross-site scripting attack

Question 30

What's the purpose of the ORDER BY clause in SQL?

Accepted Answer

Sorts query results in ascending or descending order.

Answer

Groups query results.

Answer

Filters query results.

Question 31

Which SQL command retrieves data from a table?

Accepted Answer

SELECT

Answer

DELETE

Answer

UPDATE

Answer

INSERT

Question 32

Which SQL data type is used for storing dates and times?

Accepted Answer

DATETIME

Answer

VARCHAR

Answer

BOOLEAN

Answer

INT

Question 33

Which SQL clause is used to filter the rows returned by a SELECT statement?

Accepted Answer

WHERE

Answer

ORDER BY

Answer

GROUP BY

Question 34

Which SQL operator concatenates strings?

Accepted Answer

||

Answer

&

Answer

+

Question 35

Which SQL command is used to create a new table?

Accepted Answer

CREATE TABLE

Answer

INSERT INTO

Answer

DROP TABLE

Answer

ALTER TABLE

Question 36

Which SQL keyword identifies the primary key of a table?

Accepted Answer

PRIMARY KEY

Answer

UNIQUE

Answer

FOREIGN KEY

Answer

NOT NULL

Question 37

Which SQL function calculates the average of a set of values?

Accepted Answer

AVG

Answer

MIN

Answer

SUM

Answer

COUNT

Question 38

Which SQL clause groups the results of a SELECT statement?

Accepted Answer

GROUP BY

Answer

WHERE

Answer

HAVING

Answer

ORDER BY

Question 39

Which SQL command updates data in a table?

Accepted Answer

UPDATE

Answer

INSERT INTO

Answer

SELECT FROM

Answer

DELETE FROM

Question 40

Which SQL statement is used to create a new table?

Accepted Answer

CREATE TABLE

Answer

SELECT *

Answer

INSERT INTO

Answer

CREATE DATABASE

Question 41

What is the purpose of the WHERE clause in an SQL SELECT statement?

Accepted Answer

To filter the results based on a specified condition.

Answer

To limit the number of rows returned.

Answer

To sort the results in ascending order.

Answer

To group the results by a specified column.

Question 42

What is the purpose of a JOIN in SQL?

Accepted Answer

To combine rows from two or more tables based on a common column.

Answer

To update data in a table.

Answer

To create a new table.

Question 43

Which of the following is a valid aggregate function in SQL?

Accepted Answer

SUM

Answer

SELECT

Answer

JOIN

Answer

WHERE

Question 44

What is the default storage engine for MySQL?

Accepted Answer

InnoDB

Answer

Aria

Answer

MyISAM

Answer

NDB

Question 45

What is the purpose of a primary key in an SQL table?

Accepted Answer

To uniquely identify each row in a table.

Answer

To establish relationships between tables.

Answer

To index the table for faster data retrieval.

Answer

To enforce data integrity.

Question 46

Which of the following is a type of SQL injection attack?

Accepted Answer

Union-based injection

Answer

Buffer overflow

Answer

Denial-of-service

Answer

Cross-site scripting

Question 47

In SQL, which command creates a new table?

Accepted Answer

CREATE TABLE

Answer

ADD TABLE

Answer

INSERT TABLE

Question 48

Which SQL operator is used to connect two conditions, requiring both to be true?

Accepted Answer

AND

Answer

LIKE

Answer

NOT

Answer

OR

Question 49

In SQL, which command retrieves data from a table?

Accepted Answer

SELECT

Answer

FETCH

Answer

READ

Answer

GET

Question 50

Which SQL clause specifies a condition that must be met for data to be retrieved?

Accepted Answer

WHERE

Answer

IF

Answer

WHEN

Question 51

Which SQL function calculates the largest value within a set of data?

Accepted Answer

MAX()

Answer

MAXIMUM

Answer

MAXVALUE

Answer

HIGHEST

Question 52

In SQL, which statement modifies existing data in a table?

Accepted Answer

UPDATE

Answer

MODIFY

Answer

CHANGE

Answer

EDIT

Question 53

Which SQL clause groups data before applying aggregate functions?

Accepted Answer

GROUP BY

Answer

SORT BY

Answer

CLASSIFY BY

Answer

ORDER BY

Question 54

Which SQL statement combines rows from two or more tables based on a common column?

Accepted Answer

JOIN

Answer

LINK

Answer

CONNECT

Answer

MERGE

Question 55

In SQL, which command permanently removes a table from the database?

Accepted Answer

DROP TABLE

Answer

REMOVE TABLE

Answer

DELETE TABLE