Why filtering is essential in SQL - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to select only employees from the 'Sales' department.

SQL

SELECT * FROM employees WHERE department = [1];

Drag options to blanks, or click blank then click option'

A'HR'

B'Finance'

C'Marketing'

D'Sales'

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting to use quotes around the department name.

Using the wrong department name.

The WHERE clause filters rows to include only those where the department is 'Sales'.

2fill in blank

medium

Complete the code to find products with a price greater than 100.

SQL

SELECT product_name FROM products WHERE price [1] 100;

Drag options to blanks, or click blank then click option'

A<

B>

C=

D<=

Attempts:

3 left

💡 Hint

Common Mistakes

Using < instead of >.

Using = which only finds prices exactly 100.

The > operator filters products priced above 100.

3fill in blank

hard

Fix the error in the code to select customers from 'USA'.

SQL

SELECT * FROM customers WHERE country = [1];

Drag options to blanks, or click blank then click option'

A'USA'

BUSA

C"USA"

D‘USA’

Attempts:

3 left

💡 Hint

Common Mistakes

Using no quotes or double quotes around string values.

Using fancy quotes like ‘ or ’ which are invalid.

String values in SQL must be enclosed in single quotes ' '. Double quotes or no quotes cause errors.

4fill in blank

hard

Fill both blanks to select orders with quantity less than 10 and status 'pending'.

SQL

SELECT * FROM orders WHERE quantity [1] 10 AND status = [2];

Drag options to blanks, or click blank then click option'

A<

B>

C'pending'

D'completed'

Attempts:

3 left

💡 Hint

Common Mistakes

Using > instead of < for quantity.

Forgetting quotes around 'pending'.

The query filters orders where quantity is less than 10 and status is 'pending'.

5fill in blank

hard

Fill all three blanks to select employees whose age is greater than 30 and department is 'HR'.

SQL

SELECT name, age, department FROM employees WHERE age [1] 30 AND department = [2] ORDER BY [3];

Drag options to blanks, or click blank then click option'

A<

B>

C'HR'

Dage

Attempts:

3 left

💡 Hint

Common Mistakes

Using < instead of > for age.

Forgetting quotes around 'HR'.

Ordering by a wrong column.

The query filters employees older than 30 in the HR department and orders results by age.