Database in everyday apps (social media, banking) in Intro to Computing - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

How does a social media app use a database to show your friend list?

Imagine you open a social media app and see your list of friends. How does the app use a database to get this list?

A The app asks the database to find all friends linked to your user ID and sends back their names.

B The app stores all friends on your phone and never asks the database.

C The app sends your password to the database to get the friend list.

D The app randomly picks names from the database without checking your user ID.

💡 Hint

Think about how the app knows which friends belong to you.

The app queries the database using your user ID to find friends linked to you. This is how it gets the correct friend list.

❓ trace

intermediate

Trace the steps when you transfer money in a banking app

Follow the steps below and choose what happens right after the app checks your balance:

1. You enter amount to send.
2. App checks your balance.
3. ???

A The app sends a message to your friend without checking balances.

B The app asks you to enter your password again before checking balance.

C The app updates your balance and the receiver's balance in the database.

D The app deletes your account from the database.

💡 Hint

Think about what must happen after confirming you have enough money.

After confirming your balance is enough, the app updates both your and the receiver's balances in the database to reflect the transfer.

❓ Comparison

advanced

Compare how social media and banking apps use databases differently

Which statement best describes a key difference in how social media and banking apps use databases?

A Social media databases focus on fast access to many user connections, while banking databases focus on secure, accurate transaction records.

B Banking databases store only pictures, while social media databases store only numbers.

C Social media apps do not use databases, but banking apps do.

D Both apps use databases only to store passwords.

💡 Hint

Think about what each app needs most from its database.

Social media apps need to quickly access many user connections, while banking apps require secure and accurate transaction records.

❓ identification

advanced

Identify the database operation when you 'like' a post on social media

What database operation happens when you click 'like' on a post?

A The database sends an email to all users.

B The database deletes the post permanently.

C The database creates a new user account.

D The database updates the post's like count by adding your user ID to the list of likes.

💡 Hint

Think about what changes in the database when you like something.

Clicking 'like' updates the post's record in the database to include your user ID in the list of likes, increasing the like count.

🚀 Application

expert

What happens if a banking app database loses connection during a money transfer?

During a money transfer, the app loses connection to the database after deducting money from your account but before adding it to the receiver's account. What is the likely result?

A The transfer completes successfully without any issues.

B Your money is deducted but the receiver does not get it, causing an inconsistent state.

C The app automatically refunds the money without database access.

D The receiver gets double the money.

💡 Hint

Think about what happens if only part of a transaction is saved.

If the database connection is lost mid-transfer, only part of the transaction may be saved, causing money to be deducted from your account but not added to the receiver's, leading to errors.