Why databases over files in SQL - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to select all records from the users table.

SQL

SELECT [1] FROM users;

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

AALL

BALL_COLUMNS

CEVERY

D*

Attempts:

3 left

💡 Hint

Common Mistakes

Using ALL or EVERY instead of * to select all columns.

The asterisk (*) selects all columns from the table.

2fill in blank

medium

Complete the code to find records where age is greater than 30.

SQL

SELECT * FROM employees 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 '<' or '=' instead of '>' for greater than comparison.

The '>' operator means 'greater than' in SQL.

3fill in blank

hard

Fix the error in the SQL query to count the number of orders.

SQL

SELECT COUNT([1]) FROM orders;

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

A*

Border_id

Call

Dorders

Attempts:

3 left

💡 Hint

Common Mistakes

Using COUNT(orders) or COUNT(all) which are invalid.

Using COUNT(*) counts all rows in the table.

4fill in blank

hard

Fill both blanks to select names and ages of employees older than 25.

SQL

SELECT [1], [2] FROM employees WHERE age > 25;

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

Aname

Bage

Csalary

Ddepartment

Attempts:

3 left

💡 Hint

Common Mistakes

Selecting salary or department instead of name and age.

We select 'name' and 'age' columns to see employees' names and ages.

5fill in blank

hard

Fill all three blanks to create a dictionary of product names and prices where price is above 100.

SQL

SELECT [1], [2] FROM products WHERE [3] > 100;

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

Aproduct_name

Bprice

Dquantity

Attempts:

3 left

💡 Hint

Common Mistakes

Using quantity instead of price in the WHERE clause.

Select product_name and price columns where price is greater than 100.