Database in everyday apps (social media, banking) in Intro to Computing - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to select all records from a database table named 'users'.

Intro to Computing

SELECT [1] FROM users;

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

Aname

B*

Cuser_id

Demail

Attempts:

3 left

💡 Hint

Common Mistakes

Using a specific column name when the task asks for all columns.

Leaving the blank empty.

The asterisk (*) means 'all columns' in SQL, so this query selects all data from the 'users' table.

2fill in blank

medium

Complete the code to find users with the username 'alice'.

Intro to Computing

SELECT * FROM users WHERE username [1] 'alice';

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

A=

BLIKE

C!=

DIN

Attempts:

3 left

💡 Hint

Common Mistakes

Using '!=' which means 'not equal'.

Using 'LIKE' without wildcards for exact match.

The '=' operator checks for exact equality, so this query finds users whose username is exactly 'alice'.

3fill in blank

hard

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

Intro to Computing

SELECT COUNT([1]) FROM transactions;

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

Atransaction_id

Bdate

C*

Damount

Attempts:

3 left

💡 Hint

Common Mistakes

Counting a specific column which may have NULLs and cause incorrect counts.

Leaving the parentheses empty.

Using COUNT(*) counts all rows in the table, which is the correct way to count transactions.

4fill in blank

hard

Fill both blanks to select usernames and emails of users who have logged in more than 5 times.

Intro to Computing

SELECT [1], [2] FROM users WHERE login_count > 5;

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

Ausername

Bemail

Cpassword

Duser_id

Attempts:

3 left

💡 Hint

Common Mistakes

Selecting password instead of email.

Selecting user_id instead of username.

This query selects the username and email columns for users with more than 5 logins.

5fill in blank

hard

Fill all three blanks to create a dictionary comprehension that maps user IDs to their email addresses for users with active status.

Intro to Computing

user_emails = { [3]['[1]']: [3]['[2]'] for [3] in users if [3]['status'] == 'active' }

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

Auser_id

Bemail

Cuser

Did

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'id' instead of 'user_id' as key.

Using 'users' as loop variable instead of a single user.

Mixing up keys and values in the comprehension.

This comprehension creates a dictionary where each key is a user_id and the value is the user's email, but only for active users.