What is SQL - Interactive Quiz & Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to select all columns from the table named 'employees'.

SQL

SELECT [1] FROM employees;

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

A*

BALL

Ceverything

Dcolumns

Attempts:

3 left

💡 Hint

Common Mistakes

Using words like ALL or columns instead of *

Leaving the blank empty

The asterisk (*) means select all columns from the table.

2fill in blank

medium

Complete the code to filter rows where the age is greater than 30.

SQL

SELECT * FROM users WHERE age [1] 30;

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

A=

B>

C<

D<=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '=' which selects only age exactly 30

Using '<' which selects ages less than 30

The '>' operator means 'greater than', so it filters ages above 30.

3fill in blank

hard

Fix the error in the code to count the number of rows in the 'orders' table.

SQL

SELECT COUNT([1]) FROM orders;

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

Aall

Border_id

Crows

D*

Attempts:

3 left

💡 Hint

Common Mistakes

Using a column name that might have NULLs and miss some rows

Using words like 'all' or 'rows' which are not valid here

Using COUNT(*) counts all rows regardless of column values.

4fill in blank

hard

Fill both blanks to select the name and age from 'students' where age is less than 20.

SQL

SELECT [1], age FROM students WHERE age [2] 20;

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

Aname

B>

C<

Dstudent_name

Attempts:

3 left

💡 Hint

Common Mistakes

Using '>' instead of '<' for filtering age

Using wrong column names like 'student_name'

We select the 'name' column and filter ages less than 20 using '<'.

5fill in blank

hard

Fill all three blanks to select the city and count of customers from 'customers' grouped by city having more than 5 customers.

SQL

SELECT [1], COUNT([2]) FROM customers GROUP BY [3] HAVING COUNT([2]) > 5;

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

Acity

B*

Dcustomer_id

Attempts:

3 left

💡 Hint

Common Mistakes

Using different columns for grouping and selecting

Counting a specific column that might have NULLs

We select 'city', count the 'customer_id' column, group by 'city' to get counts per city, and filter groups with more than 5 customers.