Databases in App Inventor Quiz
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Questions and Answers

What is used to identify the data stored in the database for a user's vote?

  • The IP address of the user
  • The user's phone number
  • The user's email (correct)
  • The vote category

    • What type of storage does TinyWebDB use compared to TinyDB?

  • Memory storage
  • Cloud storage
  • Web-based storage (correct)
  • Local storage on the device

    • What is the primary function of the TinyWebDB.GetValue block?

  • To delete a value from the database
  • To request a value from the web database (correct)
  • To immediately retrieve a stored value
  • To store values into the database

    • What happens when a TinyWebDB.GetValue request is fulfilled?

    <p>TinyWebDB.GotValue event is triggered</p> Signup and view all the answers

    How is the storage structure of a user's vote presented in the database?

    <p>As a key-value pair</p> Signup and view all the answers

    Which block represents the functionality of immediate value retrieval in TinyDB?

    <p>TinyDB.GetValue</p> Signup and view all the answers

    What must be handled when using TinyWebDB to receive data?

    <p>Request delays and handling of responses</p> Signup and view all the answers

    What is an example of a tag-value pair when a user votes for 'Pizza'?

    <p><a href="mailto:[email protected]">[email protected]</a>, Pizza</p> Signup and view all the answers

    What is the main advantage of using a database in an app?

    <p>It provides persistent storage of information.</p> Signup and view all the answers

    What programming technique is often not taught until upper-level courses?

    <p>Database programming</p> Signup and view all the answers

    Which of the following components simplifies database communication in App Inventor?

    <p>Store and get operations</p> Signup and view all the answers

    What happens to data stored in variables and component properties when the app is closed?

    <p>It is temporarily lost if not stored in a database.</p> Signup and view all the answers

    What is a common function of databases used in applications like Facebook or Amazon?

    <p>To store user account information and transaction history.</p> Signup and view all the answers

    In what scenario is the data considered persistent?

    <p>When successfully stored in a database.</p> Signup and view all the answers

    Which database is commonly used in many programming environments for app development?

    <p>Oracle</p> Signup and view all the answers

    What should happen to a user's custom message in the No Texting While Driving app once it is entered?

    <p>It should remain unchanged even after closing the app.</p> Signup and view all the answers

    What is the main purpose of the default web database?

    <p>For development and experimentation with App Inventor.</p> Signup and view all the answers

    How does the voting app manage user votes?

    <p>Each new vote submitted by a user overwrites their previous vote.</p> Signup and view all the answers

    What is required from users when they enter the voting app?

    <p>Users are prompted to enter their email address.</p> Signup and view all the answers

    What happens if another app writes to the default web database?

    <p>There is a risk that data could be overwritten.</p> Signup and view all the answers

    What is needed to view the votes from others in the group within the app?

    <p>Users can freely view the votes at any time.</p> Signup and view all the answers

    Which component is specifically mentioned as part of submitting a vote in the app?

    <p>VoteTextBox</p> Signup and view all the answers

    What aspect of TinyWebDB is highlighted in relation to the default database?

    <p>It is limited in size and accessible by all developers.</p> Signup and view all the answers

    What will users learn later in the chapter regarding web databases?

    <p>How to create their own web database.</p> Signup and view all the answers

    What is the purpose of the Notifier component in the voting app?

    <p>To prompt the user for their email address.</p> Signup and view all the answers

    Why should GetValue be called after obtaining the user's email address?

    <p>It allows for ensuring the user is accounted for in the voter list.</p> Signup and view all the answers

    What action should be taken if the voter list received from the database is empty?

    <p>Create a new voter list with the user's email.</p> Signup and view all the answers

    What is the first step when the app initializes according to the logic described?

    <p>Prompt the user for their email address.</p> Signup and view all the answers

    Which component of the app checks if the data retrieved is a list?

    <p>GotValue event handler.</p> Signup and view all the answers

    What should happen if the user's email is not present in the voter list?

    <p>The user's email should be added to the voter list.</p> Signup and view all the answers

    What does the app do after successfully retrieving the voter list?

    <p>Updates the voter list in the database if necessary.</p> Signup and view all the answers

    What condition must be met for the app to consider that it has successfully retrieved data?

    <p>The data must be a non-empty list.</p> Signup and view all the answers

    What action is taken if the user is not found in the current list?

    <p>The user's email is added to the list and stored.</p> Signup and view all the answers

    What happens if no voter list has been previously created?

    <p>A new voterList is created with the current user’s email.</p> Signup and view all the answers

    How are the votes submitted when a user clicks the VoteButton?

    <p>Votes are submitted along with an email and a tag.</p> Signup and view all the answers

    What type of data structure is used to store the votes retrieved from the database?

    <p>A list</p> Signup and view all the answers

    How does the application check the votes for each individual user in the voter list?

    <p>Through a for each loop with a request to TinyWebDB1.GetValue.</p> Signup and view all the answers

    What occurs after the app retrieves the votes from the database?

    <p>Votes will not be processed until all data is received.</p> Signup and view all the answers

    Which of the following describes the structure of the database entries shown in the example?

    <p>Tags are used to organize votes in pairs.</p> Signup and view all the answers

    What is the intended outcome of creating a new voterList when no users have registered?

    <p>To encourage participation from new users.</p> Signup and view all the answers

    Study Notes

    Databases in App Inventor

    • App Inventor simplifies database communication by offering components that make storing and retrieving data straightforward.
    • Apps can store data directly on the Android device or in a centralized database on the web, allowing data sharing.
    • Data stored in variables and component properties is temporary and lost when the app closes.
    • Databases provide persistent data storage, meaning data remains available even after app closure.
    • TinyWebDB is a web-based database service that allows App Inventor apps to share data.
    • TinyWebDB.StoreValue block stores data in the web database.
    • The tag identifies the data, and the value is the data itself.
    • The default TinyWebDB is limited in size and accessible to all App Inventor programmers.
    • It is suitable for exploration and early stages of development, but not recommended fot production apps.

    Using TinyWebDB for Voting App

    • The voting app utilizes TinyWebDB to store and retrieve user votes.
    • Users provide their email address, which serves as the tag for their vote.
    • The app retrieves and displays all votes from the database.
    • TinyWebDB.GetValue requests data from the web database, but doesn't immediately return a value.
    • TinyWebDB.GotValue event is triggered when data arrives from the web database.
    • The app prompts the user for their email address before retrieving the voter list from the database.
    • The GotValue event handler checks if the user's email is in the existing voter list.
    • If the user’s email is not in the list, it is added to the voter list and stored back in the database.
    • If there's no voter list yet, the user's email is added as the first item to the list.

    Requesting Votes with Various Tags

    • The app retrieves and displays each user's vote using a for each loop.
    • The voting app utilizes a for each loop to retrieve votes for each user in the voter list.
    • The loop sends a GetValue request to the database for each email address in the voter list.
    • The votes are not added to the currentVotesList until they arrive through GotValue events.

    Displaying Votes

    • The app retrieves votes from the database using multiple GetValue requests.
    • The votes are only added to the currentVotesList after they arrive through the GotValue events.
    • The votes can be displayed in a visual component like a listview to showcase the voting results.

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    Related Documents

    chapter22.pdf

    Description

    Test your knowledge on how databases are used in App Inventor, focusing on TinyWebDB and its applications, such as in a voting app. Understand the differences between temporary data storage and persistent storage options. This quiz will also cover the limitations and functionalities of TinyWebDB.

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