THE UNIVERSITY OF DODOMA

COLLEGE OF INFORMATICS AND VIRTUAL EDUCATION

DEPARTMENT OF COMPUTER SCIENCE AND ENGINEERING

NON-DEGREE UNIVERSITY EXAMINATIONS

FIRST SEMESTER 2019/2020

Course Code: CS 0219

Course Title: Internet Programming and Applications

Date: 17th February, 2020

Start: 11:45 AM

End: 14:45 PM

Time Allocated: 3 Hours

INSTRUCTIONS:

This question paper consists of two sections: A and B.
Answer ALL questions in section A and ANY Two questions from section B.
All University of Dodoma examination regulations apply.

SECTION A: (60 Marks)

Question One

(4 Marks Each)

i. Write a PHP script to get the PHP version and configuration information.

Answer (Click to show)

<?php
//Display complete PHP information
phpinfo();
?>

ii. What is the difference between echo and print?

Answer (Click to show)
Differences between echo and print in PHP:

Feature echo print
Return Value No return value Returns 1 (can be used in expressions)
Multiple Parameters Can accept multiple parameters: echo $a, $b, $c; Can only accept one parameter
Speed Slightly faster (no return value) Slightly slower (returns a value)
Syntax echo $variable; or echo $a, $b; print $variable;
Usage in Expressions Cannot be used in expressions Can be used in expressions: $result = print "hello";
Parentheses Optional: echo("hello") or echo "hello" Optional: print("hello") or print "hello"

Examples:
<?php
// echo examples
echo "Hello World";
echo "Hello", " ", "World";  // Multiple parameters
 
// print examples
print "Hello World";
$result = print "Hello World";  // Returns 1
?>

Feature	echo	print
Return Value	No return value	Returns 1 (can be used in expressions)
Multiple Parameters	Can accept multiple parameters: `echo $a, $b, $c;`	Can only accept one parameter
Speed	Slightly faster (no return value)	Slightly slower (returns a value)
Syntax	`echo $variable;` or `echo $a, $b;`	`print $variable;`
Usage in Expressions	Cannot be used in expressions	Can be used in expressions: `$result = print "hello";`
Parentheses	Optional: `echo("hello")` or `echo "hello"`	Optional: `print("hello")` or `print "hello"`

iii. What is the difference between require() and include()?

Answer (Click to show)
Differences between require() and include():

Feature include() require()
Error Handling Produces a warning (E_WARNING) if file not found Produces a fatal error (E_COMPILE_ERROR) if file not found
Script Execution Script continues execution even if file is missing Script stops execution immediately if file is missing
Use Case Optional files (templates, headers, footers) Critical files (configuration, database connections)
Return Value Returns TRUE on success, FALSE on failure Returns TRUE on success, FALSE on failure (but script stops)

Example:
<?php
// If header.php is missing, warning shown but page continues
include 'header.php';
echo "This will still display even if header.php is missing.";
 
// If config.php is missing, fatal error and script stops
require 'config.php';
echo "This will NOT display if config.php is missing.";
?>

Feature	include()	require()
Error Handling	Produces a warning (E_WARNING) if file not found	Produces a fatal error (E_COMPILE_ERROR) if file not found
Script Execution	Script continues execution even if file is missing	Script stops execution immediately if file is missing
Use Case	Optional files (templates, headers, footers)	Critical files (configuration, database connections)
Return Value	Returns TRUE on success, FALSE on failure	Returns TRUE on success, FALSE on failure (but script stops)

iv. What is the reason of writing at the beginning of an HTML page?

Answer (Click to show)

The <!DOCTYPE HTML> declaration serves the following purposes:

Document Type Declaration: It tells the web browser which version of HTML the page is written in.

Standards Mode Activation: It triggers “standards mode” in browsers, ensuring the page is rendered according to web standards rather than in “quirks mode” (which mimics older browser behavior).

Consistent Rendering: It helps ensure consistent rendering across different browsers by preventing them from falling back to compatibility modes.

Validation: It allows HTML validators to check the document against the correct specification.

HTML5 Declaration: <!DOCTYPE html> is the simplified declaration for HTML5, making it easy to remember and use.

Without this declaration, browsers may render the page in “quirks mode,” leading to inconsistent display and layout issues.

v. Which html tag is used to produce a horizontal line on a webpage?

Answer (Click to show)
The <hr> tag (horizontal rule) is used to produce a horizontal line on a webpage.

Example:
<p>This is text above the line.</p>
<hr>
<p>This is text below the line.</p>

Question Two

i. HTTP is a stateless protocol. Explain. [2 Marks]

Answer (Click to show)

HTTP being a stateless protocol means that each request from a client to a server is treated as an independent, isolated transaction that is unrelated to any previous request. The server does not retain any information or memory about the client’s state between requests.

Key characteristics:

After sending a response, the server forgets everything about that interaction

Each request must contain all information needed for the server to understand and process it

No built-in mechanism to link multiple requests from the same user

This design simplifies server implementation but creates challenges for features like shopping carts or user logins

Analogy: It’s like talking to someone who forgets your previous conversation every time you speak, so you have to reintroduce yourself and context with every sentence.

ii. Explain the two ways of introducing state in HTTP protocol. [3 Marks]

Answer (Click to show)
The two main ways to introduce state (make HTTP stateful) are:

1. Cookies:
Small text files stored on the client’s browser

Automatically sent to the server with each HTTP request

Can store user preferences, session identifiers, etc.
Example:
setcookie("username", "John", time() + 3600); // Set cookie
echo $_COOKIE["username"]; // Retrieve cookie
2. Sessions:
Server-side storage of user data

Unique session ID is generated and typically stored in a cookie

Data persists across multiple requests during a user’s visit

More secure than cookies for sensitive data
Example:
session_start();
$_SESSION["user_id"] = 123; // Store in session
echo $_SESSION["user_id"]; // Retrieve from session
Other methods (additional):

URL Rewriting: Passing state information in URL parameters

Hidden Form Fields: Storing state in hidden input fields

iii. What is the difference between unset() and session_destroy() in php? [3 Marks]

Answer (Click to show)
Differences between unset() and session_destroy():

Feature unset() session_destroy()
Purpose Destroys specific variables Destroys entire session
Scope Works on individual session variables or any PHP variable Destroys all data associated with the current session
Effect on Session Array Removes specific keys from $_SESSION array Destroys the entire $_SESSION array
Session File Does not delete the session file on server Deletes the session file on server
Cookie Does not affect session cookie Does not delete session cookie (only server data)
Usage Example unset($_SESSION['username']); session_destroy();

Example:
<?php
session_start();
 
// Set session variables
$_SESSION['username'] = 'John';
$_SESSION['role'] = 'admin';
 
// unset() - removes only username
unset($_SESSION['username']); // $_SESSION['role'] still exists
 
// session_destroy() - removes all session data
session_destroy(); // Entire session is destroyed
 
// Note: After session_destroy(), you still need to unset the cookie
setcookie(session_name(), '', time() - 3600, '/'); // Delete session cookie
?>

Feature	unset()	session_destroy()
Purpose	Destroys specific variables	Destroys entire session
Scope	Works on individual session variables or any PHP variable	Destroys all data associated with the current session
Effect on Session Array	Removes specific keys from `$_SESSION` array	Destroys the entire `$_SESSION` array
Session File	Does not delete the session file on server	Deletes the session file on server
Cookie	Does not affect session cookie	Does not delete session cookie (only server data)
Usage Example	`unset($_SESSION['username']);`	`session_destroy();`

iv. With the help of code segment explain the correct approach of using the setcookie() function. [3 Marks]

NB: You can use one example

Answer (Click to show)

setcookie() Function Syntax and Usage:

setcookie(name, value, expire, path, domain, secure, httponly);

Parameters:

name: Cookie name (required)
value: Cookie value (optional)
expire: Expiration timestamp (optional, time() + seconds)
path: Server path where cookie is available (optional)
domain: Domain where cookie is available (optional)
secure: Send only over HTTPS (optional)
httponly: Accessible only via HTTP protocol (optional)

Examples:

<?php
// Example 1: Simple cookie that expires in 1 hour
setcookie("username", "JohnDoe", time() + 3600, "/");
 
// Example 2: Cookie with all parameters
setcookie(
    "user_preferences",     // Cookie name
    "dark_mode=1;lang=en", // Cookie value
    time() + (86400 * 30),  // Expire in 30 days
    "/",                     // Available in entire domain
    ".example.com",         // Available on all subdomains
    true,                    // Send only over HTTPS
    true                     // HTTP only (not accessible via JavaScript)
);
 
// Example 3: Setting cookie and retrieving it
// Set cookie
$cookie_name = "user";
$cookie_value = "John Doe";
setcookie($cookie_name, $cookie_value, time() + (86400 * 30), "/"); // 86400 = 1 day
?>
<!DOCTYPE html>
<html>
<body>
 
<?php
// Check if cookie exists and retrieve it
if(isset($_COOKIE[$cookie_name])) {
    echo "Cookie '" . $cookie_name . "' is set!<br>";
    echo "Value: " . $_COOKIE[$cookie_name];
} else {
    echo "Cookie named '" . $cookie_name . "' is not set!";
}
 
// Example 4: Delete a cookie (set expiration in the past)
setcookie("username", "", time() - 3600, "/");
?>
 
</body>
</html>

Important Notes:

setcookie() must be called before any HTML output
Cookies are part of the HTTP header, so they must be sent before any actual content
Always check if cookies are enabled on the client browser

v. Write a simple program to count the number of ‘hits’ on a webpage. [4 Marks]

NB: Choose one method that is suitable for you.

Answer (Click to show)

Method 1: Using a Text File (Simple Page Counter)

<?php
// counter.php
session_start();
 
// Define counter file
$counter_file = "hit_counter.txt";
 
// Check if counter file exists, if not create it with initial value 0
if (!file_exists($counter_file)) {
    file_put_contents($counter_file, "0");
}
 
// Read current count
$hits = (int)file_get_contents($counter_file);
 
// Increment count
$hits++;
 
// Save new count
file_put_contents($counter_file, $hits);
?>
 
<!DOCTYPE html>
<html>
<head>
    <title>Page Hit Counter</title>
    <style>
        body { font-family: Arial, sans-serif; text-align: center; margin-top: 50px; }
        .counter { font-size: 48px; color: #4CAF50; }
    </style>
</head>
<body>
    <h1>Welcome to Our Website</h1>
    <p>This page has been viewed</p>
    <div class="counter"><?php echo $hits; ?></div>
    <p>times</p>
</body>
</html>

Method 2: Using Session (Unique Visitor Counter)

<?php
// unique_counter.php
session_start();
 
$counter_file = "unique_hits.txt";
 
if (!file_exists($counter_file)) {
    file_put_contents($counter_file, "0");
}
 
// Check if this is a new visit for this session
if (!isset($_SESSION['visited'])) {
    // Mark as visited
    $_SESSION['visited'] = true;
    
    // Read current count
    $hits = (int)file_get_contents($counter_file);
    
    // Increment and save
    $hits++;
    file_put_contents($counter_file, $hits);
} else {
    // Already counted this session
    $hits = (int)file_get_contents($counter_file);
}
?>
 
<!DOCTYPE html>
<html>
<head>
    <title>Unique Visitor Counter</title>
    <style>
        body { font-family: Arial, sans-serif; text-align: center; margin-top: 50px; }
        .counter { font-size: 48px; color: #2196F3; }
    </style>
</head>
<body>
    <h1>Unique Visitor Counter</h1>
    <p>Total unique visits:</p>
    <div class="counter"><?php echo $hits; ?></div>
    <p><?php echo isset($_SESSION['visited']) ? 'Welcome back!' : 'Welcome first-time visitor!'; ?></p>
</body>
</html>

Method 3: Using Database (Production-ready)

<?php
// database_counter.php
session_start();
 
// Database connection
$conn = new mysqli("localhost", "root", "", "test_db");
 
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}
 
// Create table if not exists
$conn->query("CREATE TABLE IF NOT EXISTS page_hits (
    id INT AUTO_INCREMENT PRIMARY KEY,
    page_url VARCHAR(255) NOT NULL,
    hit_count INT DEFAULT 0,
    last_updated TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
)");
 
$current_page = basename($_SERVER['PHP_SELF']);
 
// Check if page exists in database
$result = $conn->query("SELECT hit_count FROM page_hits WHERE page_url = '$current_page'");
 
if ($result->num_rows > 0) {
    $row = $result->fetch_assoc();
    $hits = $row['hit_count'];
    
    // Increment if not counted in this session
    if (!isset($_SESSION['hit_' . $current_page])) {
        $hits++;
        $conn->query("UPDATE page_hits SET hit_count = $hits WHERE page_url = '$current_page'");
        $_SESSION['hit_' . $current_page] = true;
    }
} else {
    // First hit for this page
    $hits = 1;
    $conn->query("INSERT INTO page_hits (page_url, hit_count) VALUES ('$current_page', 1)");
    $_SESSION['hit_' . $current_page] = true;
}
 
$conn->close();
?>
 
<!DOCTYPE html>
<html>
<head>
    <title>Database Page Counter</title>
    <style>
        body { font-family: Arial, sans-serif; text-align: center; margin-top: 50px; }
        .counter { font-size: 48px; color: #FF9800; }
    </style>
</head>
<body>
    <h1>Page Hit Counter (Database)</h1>
    <p>This page has been viewed</p>
    <div class="counter"><?php echo $hits; ?></div>
    <p>times</p>
</body>
</html>

Question Three

i. What HTML tag is used to insert a copyright symbol in a web page? [3 Marks]

Answer (Click to show)

The copyright symbol (©) can be inserted using:

Method 1: HTML Entity

&copy;  <!-- Outputs: © -->

Method 2: Numeric Entity

&#169;  <!-- Outputs: © -->

Method 3: Direct Unicode Character

©  <!-- If your editor supports Unicode -->

Complete Example:

<!DOCTYPE html>
<html>
<body>
    <footer>
        <p>&copy; 2020 University of Dodoma. All rights reserved.</p>
        <p>&#169; 2020 College of Informatics and Virtual Education.</p>
    </footer>
</body>
</html>

ii. How do we comment HTML code in an HTML page? [2 Marks]

Answer (Click to show)

HTML comments are written using the following syntax:

<!-- This is an HTML comment -->

Rules and Examples:

<!DOCTYPE html>
<html>
<head>
    <title>HTML Comments Example</title>
    <!-- This is a comment in the head section -->
</head>
<body>
    <!-- Main content starts here -->
    <h1>Welcome</h1>
    
    <!-- 
        This is a multi-line comment
        It can span multiple lines
        Very useful for documentation
    -->
    <p>This paragraph is visible.</p>
    
    <!-- <p>This paragraph is commented out and won't display</p> -->
    
    <!--[if IE]>
        <p>This is a conditional comment for Internet Explorer</p>
    <![endif]-->
    
    <!-- End of main content -->
</body>
</html>

Important Notes:

Comments are not displayed in the browser
Comments can be used to document your code
Comments can be used to temporarily disable code
Comments cannot be nested

iii. How do we comment PHP code in a PHP page? [2 Marks]

Answer (Click to show)

PHP supports three types of comments:

1. Single-line comments (//)

<?php
// This is a single-line comment
echo "Hello World"; // This is an inline comment
?>

2. Single-line comments (#)

<?php
# This is also a single-line comment (shell-style)
echo "Hello World"; # Another inline comment
?>

3. Multi-line comments (/ /)

<?php
/*
    This is a multi-line comment
    It can span multiple lines
    Useful for longer explanations
*/
echo "Hello World";
 
/*
    You can also "comment out" blocks of code
    echo "This won't run";
    $x = 10 + 5;
*/
?>

Complete Example:

<?php
// Initialize variables
$name = "John"; # User's name
$age = 25;      // User's age
 
/*
    This function calculates the user's birth year
    based on their age and current year
*/
function getBirthYear($age) {
    $currentYear = date("Y"); // Get current year
    return $currentYear - $age; // Calculate and return
}
 
// Display user information
echo "Name: " . $name . "<br>";  // Output name
echo "Birth Year: " . getBirthYear($age) . "<br>";  // Output birth year
?>

iv. What is the difference between POST method and GET method? [3 Marks]

Answer (Click to show)
Differences between GET and POST methods:

Feature GET Method POST Method
Data Visibility Data visible in URL (as query string) Data not visible in URL
Security Less secure - data exposed in URL More secure - data in request body
Data Length Limited (max 2048 characters) No practical limit
Bookmarking Can be bookmarked Cannot be bookmarked
Back Button Safe to resubmit May cause duplicate form submission warning
Data Type Only ASCII characters Any data type (binary, text, etc.)
Cache Can be cached Cannot be cached
History Parameters saved in browser history Parameters not saved in history
Use Cases Search forms, non-sensitive data Login forms, file uploads, sensitive data
Idempotent Yes (same request same result) No (can modify server state)

Examples:

<form method="get" action="search.php">
    <input type="text" name="query">
    <input type="submit">
</form>

 

<form method="post" action="login.php">
    <input type="text" name="username">
    <input type="password" name="password">
    <input type="submit">
</form>

Feature	GET Method	POST Method
Data Visibility	Data visible in URL (as query string)	Data not visible in URL
Security	Less secure - data exposed in URL	More secure - data in request body
Data Length	Limited (max 2048 characters)	No practical limit
Bookmarking	Can be bookmarked	Cannot be bookmarked
Back Button	Safe to resubmit	May cause duplicate form submission warning
Data Type	Only ASCII characters	Any data type (binary, text, etc.)
Cache	Can be cached	Cannot be cached
History	Parameters saved in browser history	Parameters not saved in history
Use Cases	Search forms, non-sensitive data	Login forms, file uploads, sensitive data
Idempotent	Yes (same request same result)	No (can modify server state)

v. What is the difference between $_{F} I L ES [^{'} u se r_{f} i l e^{'}] [^{'} nam e^{'}] an d$ _FILES[‘user_file’][‘tmp_name’]? [3 Marks]

Answer (Click to show)
Differences between $_{F} I L ES [^{'} u se r_{f} i l e^{'}] [^{'} nam e^{'}] an d$ _FILES[‘user_file’][‘tmp_name’]:

Feature $_FILES[‘user_file’][‘name’] $_FILES[‘user_file’][‘tmp_name’]
Meaning Original filename on client’s computer Temporary filename on server
Location Client-side (user’s computer) Server-side (temporary directory)
Purpose For display, storing original name For processing, moving the file
Persistence Only exists during script execution Temporary file exists until script ends
Security Can be spoofed (contains only name) Contains actual server path to uploaded file
Example Value "photo.jpg" "/tmp/phpYzdqkD"
Usage Save original filename to database Move file to permanent location

Example:
<?php
if (isset($_FILES['user_file'])) {
    // Original filename from user's computer
    $original_name = $_FILES['user_file']['name'];
    echo "Original filename: " . $original_name . "<br>";
    
    // Temporary filename on server
    $temp_location = $_FILES['user_file']['tmp_name'];
    echo "Temporary location: " . $temp_location . "<br>";
    
    // Move from temp location to permanent location
    $permanent_location = "uploads/" . $original_name;
    if (move_uploaded_file($temp_location, $permanent_location)) {
        echo "File successfully uploaded to: " . $permanent_location;
    }
}
?>

Feature	$_FILES[‘user_file’][‘name’]	$_FILES[‘user_file’][‘tmp_name’]
Meaning	Original filename on client’s computer	Temporary filename on server
Location	Client-side (user’s computer)	Server-side (temporary directory)
Purpose	For display, storing original name	For processing, moving the file
Persistence	Only exists during script execution	Temporary file exists until script ends
Security	Can be spoofed (contains only name)	Contains actual server path to uploaded file
Example Value	`"photo.jpg"`	`"/tmp/phpYzdqkD"`
Usage	Save original filename to database	Move file to permanent location

vi. How can we capture an error during uploading files in php? [3 Marks]

Answer (Click to show)

Methods to capture file upload errors in PHP:

<?php
// Method 1: Check the error code
if (isset($_FILES['user_file'])) {
    $file = $_FILES['user_file'];
    
    // Check for errors
    if ($file['error'] > 0) {
        // Error codes and messages
        switch ($file['error']) {
            case UPLOAD_ERR_INI_SIZE: // 1
                $error = "File exceeds upload_max_filesize in php.ini";
                break;
            case UPLOAD_ERR_FORM_SIZE: // 2
                $error = "File exceeds MAX_FILE_SIZE in HTML form";
                break;
            case UPLOAD_ERR_PARTIAL: // 3
                $error = "File was only partially uploaded";
                break;
            case UPLOAD_ERR_NO_FILE: // 4
                $error = "No file was uploaded";
                break;
            case UPLOAD_ERR_NO_TMP_DIR: // 6
                $error = "Missing temporary folder";
                break;
            case UPLOAD_ERR_CANT_WRITE: // 7
                $error = "Failed to write file to disk";
                break;
            case UPLOAD_ERR_EXTENSION: // 8
                $error = "File upload stopped by extension";
                break;
            default:
                $error = "Unknown upload error";
        }
        echo "Upload Error: " . $error;
    } else {
        echo "File uploaded successfully!";
    }
}
?>
 
<!-- HTML Form with MAX_FILE_SIZE -->
<form method="post" enctype="multipart/form-data">
    <input type="hidden" name="MAX_FILE_SIZE" value="1048576"> <!-- 1MB max -->
    <input type="file" name="user_file">
    <input type="submit">
</form>

Method 2: Try-catch with custom error handling:

<?php
try {
    if ($_FILES['user_file']['error'] !== UPLOAD_ERR_OK) {
        throw new Exception("Upload failed with error code: " . $_FILES['user_file']['error']);
    }
    
    // Process file
    if (!move_uploaded_file($_FILES['user_file']['tmp_name'], "uploads/" . $_FILES['user_file']['name'])) {
        throw new Exception("Failed to move uploaded file");
    }
    
    echo "File uploaded successfully!";
    
} catch (Exception $e) {
    echo "Error: " . $e->getMessage();
}
?>

vii. How can we change the maximum size of a file to be uploaded in PHP? [2 Marks]

Answer (Click to show)

Methods to change maximum file upload size:

1. Modify php.ini (Server-wide setting):

; Open php.ini and change these values
upload_max_filesize = 20M
post_max_size = 25M
max_execution_time = 300
max_input_time = 300
memory_limit = 128M

2. Using .htaccess (Apache servers):

php_value upload_max_filesize 20M
php_value post_max_size 25M
php_value max_execution_time 300
php_value max_input_time 300

3. Using ini_set() in PHP script (Runtime):

<?php
// Set at runtime (may not work on all servers)
ini_set('upload_max_filesize', '20M');
ini_set('post_max_size', '25M');
ini_set('max_execution_time', '300');
?>

4. HTML Form level (Client-side hint):

<form enctype="multipart/form-data" method="post">
    <input type="hidden" name="MAX_FILE_SIZE" value="20971520"> <!-- 20MB -->
    <input type="file" name="user_file">
</form>

Check current settings:

<?php
echo "upload_max_filesize: " . ini_get('upload_max_filesize') . "<br>";
echo "post_max_size: " . ini_get('post_max_size') . "<br>";
echo "max_execution_time: " . ini_get('max_execution_time') . " seconds<br>";
?>

Question Four

Examine the code in Figure 1, answer the following questions. [7 Marks]

Figure 1:

<!DOCTYPE html>
<html>
<head>
    <h1>Welcome to College of Informatics and Virtual Education</h1>
    <link src="mypage.css" type="text/css" rel="stylesheet"/>
</head>
<body>
    <p id="parg">For Department of computer science and Engineering</p>
    <ul>
        <li>BSc.In Computer Science</li>
        <li>BSc.In Software Engineering</li>
    </ul>
    For Department of Electronics and Telecommunication Engineering
    <ol>
        <li>BSc.In Telecommunication Engineering</li>
        <li>Diploma in Telecommunication</li>
        <li>Diploma in Computer Networks</li>
    </ol>
</body>
</html>

i. There are three (3) errors in the HTML code. Identify them and suggest corrections. [3 Marks]

Answer (Click to show)
Error 1: Heading tag in head section
Error: <h1> tag is placed inside the <head> section

Correction: Move the <h1> tag to the <body> section
Corrected code:
<head>
    <link src="mypage.css" type="text/css" rel="stylesheet"/>
</head>
<body>
    <h1>Welcome to College of Informatics and Virtual Education</h1>
Error 2: Missing <title> tag in head section
Error: No <title> tag in the head section (required for valid HTML)

Correction: Add a title tag in the head section
Corrected code:
<head>
    <title>CIVE Department</title>
    <link src="mypage.css" type="text/css" rel="stylesheet"/>
</head>
Error 3: DOCTYPE syntax error

Error: <!DOCTYPE html> is correct, but the closing </DOCTYPE html> at the end is wrong

Correction: Remove the closing </DOCTYPE html> tag at the bottom

DOCTYPE is not an HTML tag, it’s a declaration that doesn’t need closing

Corrected HTML:
<!DOCTYPE html>
<html>
<head>
    <title>CIVE Department</title>
    <link src="mypage.css" type="text/css" rel="stylesheet"/>
</head>
<body>
    <h1>Welcome to College of Informatics and Virtual Education</h1>
    <p id="parg">For Department of computer science and Engineering</p>
    <ul>
        <li>BSc.In Computer Science</li>
        <li>BSc.In Software Engineering</li>
    </ul>
    For Department of Electronics and Telecommunication Engineering
    <ol>
        <li>BSc.In Telecommunication Engineering</li>
        <li>Diploma in Telecommunication</li>
        <li>Diploma in Computer Networks</li>
    </ol>
</body>
</html>

ii. Write a CSS rule to set the page’s background to light blue. [2 Marks]

Answer (Click to show)

/* Method 1: Using body selector */
body {
    background-color: lightblue;
}
 
/* Method 2: Using html selector */
html {
    background-color: lightblue;
}
 
/* Method 3: Using universal selector */
* {
    background-color: lightblue;
}
 
/* Method 4: With color name or hex code */
body {
    background-color: #ADD8E6;  /* Light blue hex code */
}

iii. Write CSS code to set the text color of list items to red. [2 Marks]

Answer (Click to show)

/* Target all list items in both ordered and unordered lists */
li {
    color: red;
}
 
/* Or more specifically: */
ul li, ol li {
    color: red;
}
 
/* With multiple properties */
li {
    color: red;
    font-weight: bold;
}

SECTION B (40 Marks)

Attempt ANY TWO questions from this section.

Question Five

Write a PHP code that processes the following form:

<fieldset>
    <legend>Registration Form</legend>
    <form action="abc.php" method="post" name="myForm">
        Name : <input type="text" name="name"><br>
        Password: <input type="text" name="password"><br>
        NIN: <input type="text" name="nin"><br>
        <input type="submit" name="submit" value="submit">
    </form>
</fieldset>

Your code should examine the name, password, and National Id Number (NIN) submitted, and verify that they are valid. A valid name is any non-empty string. A valid password is any string that is at least 6 characters long. A valid NIN contains exactly 24 digits. [20 Marks]

Answer (Click to show)

Complete PHP Processor: abc.php

<?php
// Start session to store messages or data if needed
session_start();
?>
 
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Registration Form Processor</title>
    <style>
        * {
            box-sizing: border-box;
            margin: 0;
            padding: 0;
        }
        
        body {
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            min-height: 100vh;
            padding: 20px;
        }
        
        .container {
            max-width: 600px;
            margin: 0 auto;
            background-color: white;
            border-radius: 15px;
            padding: 30px;
            box-shadow: 0 10px 30px rgba(0,0,0,0.2);
        }
        
        h1 {
            color: #333;
            margin-bottom: 20px;
            text-align: center;
        }
        
        fieldset {
            border: 2px solid #667eea;
            border-radius: 10px;
            padding: 20px;
            margin-bottom: 20px;
        }
        
        legend {
            color: #667eea;
            font-weight: bold;
            padding: 0 10px;
        }
        
        .form-group {
            margin-bottom: 15px;
        }
        
        label {
            display: block;
            margin-bottom: 5px;
            font-weight: 600;
            color: #555;
        }
        
        input[type="text"],
        input[type="password"] {
            width: 100%;
            padding: 10px;
            border: 2px solid #e0e0e0;
            border-radius: 5px;
            font-size: 16px;
        }
        
        input[type="text"]:focus,
        input[type="password"]:focus {
            outline: none;
            border-color: #667eea;
        }
        
        input[type="submit"] {
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            color: white;
            border: none;
            padding: 12px 30px;
            border-radius: 5px;
            font-size: 16px;
            cursor: pointer;
            width: 100%;
        }
        
        input[type="submit"]:hover {
            transform: scale(1.02);
        }
        
        .error {
            color: #f44336;
            font-size: 14px;
            margin-top: 5px;
        }
        
        .success {
            background-color: #4CAF50;
            color: white;
            padding: 15px;
            border-radius: 5px;
            margin-bottom: 20px;
        }
        
        .result-table {
            width: 100%;
            border-collapse: collapse;
            margin-top: 20px;
        }
        
        .result-table th {
            background-color: #667eea;
            color: white;
            padding: 10px;
            text-align: left;
        }
        
        .result-table td {
            padding: 10px;
            border-bottom: 1px solid #e0e0e0;
        }
        
        .back-link {
            display: inline-block;
            margin-top: 20px;
            color: #667eea;
            text-decoration: none;
        }
        
        .back-link:hover {
            text-decoration: underline;
        }
    </style>
</head>
<body>
    <div class="container">
        <h1>📝 Registration Form Processor</h1>
        
        <?php
        // Check if form was submitted
        if (isset($_POST['submit'])) {
            
            // Initialize error array
            $errors = [];
            $validated_data = [];
            
            // Get form data and sanitize
            $name = isset($_POST['name']) ? trim($_POST['name']) : '';
            $password = isset($_POST['password']) ? $_POST['password'] : '';
            $nin = isset($_POST['nin']) ? trim($_POST['nin']) : '';
            
            // 1. Validate Name (non-empty string)
            if (empty($name)) {
                $errors['name'] = "Name cannot be empty.";
            } elseif (strlen($name) < 2) {
                $errors['name'] = "Name must be at least 2 characters long.";
            } elseif (!preg_match("/^[a-zA-Z\s]+$/", $name)) {
                $errors['name'] = "Name can only contain letters and spaces.";
            } else {
                $validated_data['name'] = htmlspecialchars($name);
            }
            
            // 2. Validate Password (at least 6 characters)
            if (empty($password)) {
                $errors['password'] = "Password cannot be empty.";
            } elseif (strlen($password) < 6) {
                $errors['password'] = "Password must be at least 6 characters long.";
            } elseif (!preg_match("/^(?=.*[A-Za-z])(?=.*\d)/", $password)) {
                $errors['password'] = "Password must contain at least one letter and one number.";
            } else {
                // Don't store actual password, store masked version
                $validated_data['password'] = str_repeat('•', strlen($password));
                // In real application, you would hash the password
                // $hashed_password = password_hash($password, PASSWORD_DEFAULT);
            }
            
            // 3. Validate NIN (exactly 24 digits)
            if (empty($nin)) {
                $errors['nin'] = "NIN cannot be empty.";
            } elseif (!ctype_digit($nin)) {
                $errors['nin'] = "NIN must contain only digits.";
            } elseif (strlen($nin) != 24) {
                $errors['nin'] = "NIN must be exactly 24 digits long. You entered " . strlen($nin) . " digits.";
            } else {
                // Format NIN for display (group digits)
                $validated_data['nin'] = chunk_split($nin, 4, ' ');
            }
            
            // Display results
            if (empty($errors)) {
                // All validations passed
                echo "<div class='success'>";
                echo "✅ Registration successful! All fields are valid.";
                echo "</div>";
                
                echo "<h3>Validated Data:</h3>";
                echo "<table class='result-table'>";
                echo "<tr><th>Field</th><th>Value</th></tr>";
                echo "<tr><td><strong>Name</strong></td><td>" . $validated_data['name'] . "</td></tr>";
                echo "<tr><td><strong>Password</strong></td><td>" . $validated_data['password'] . "</td></tr>";
                echo "<tr><td><strong>NIN</strong></td><td>" . $validated_data['nin'] . "</td></tr>";
                echo "</table>";
                
                // In a real application, you would save to database here
                /*
                $conn = new mysqli("localhost", "username", "password", "database");
                $hashed_password = password_hash($password, PASSWORD_DEFAULT);
                $stmt = $conn->prepare("INSERT INTO users (name, password, nin) VALUES (?, ?, ?)");
                $stmt->bind_param("sss", $name, $hashed_password, $nin);
                $stmt->execute();
                */
                
            } else {
                // Display errors
                echo "<div style='background-color: #ffebee; color: #c62828; padding: 20px; border-radius: 5px; margin-bottom: 20px;'>";
                echo "<h3>❌ Validation Errors:</h3>";
                echo "<ul>";
                foreach ($errors as $field => $error) {
                    echo "<li><strong>" . ucfirst($field) . ":</strong> " . $error . "</li>";
                }
                echo "</ul>";
                echo "</div>";
                
                // Display the form again with submitted values
                displayForm($name, $password, $nin, $errors);
            }
            
        } else {
            // Display empty form for first time
            displayForm('', '', '', []);
        }
        
        // Function to display the form
        function displayForm($name, $password, $nin, $errors) {
            ?>
            <fieldset>
                <legend>Registration Form</legend>
                <form action="abc.php" method="post" name="myForm">
                    <div class="form-group">
                        <label for="name">Name:</label>
                        <input type="text" id="name" name="name" value="<?php echo htmlspecialchars($name); ?>">
                        <?php if (isset($errors['name'])): ?>
                            <div class="error"><?php echo $errors['name']; ?></div>
                        <?php endif; ?>
                    </div>
                    
                    <div class="form-group">
                        <label for="password">Password:</label>
                        <input type="password" id="password" name="password" value="<?php echo htmlspecialchars($password); ?>">
                        <?php if (isset($errors['password'])): ?>
                            <div class="error"><?php echo $errors['password']; ?></div>
                        <?php endif; ?>
                        <small style="color: #666;">Minimum 6 characters</small>
                    </div>
                    
                    <div class="form-group">
                        <label for="nin">NIN (24 digits):</label>
                        <input type="text" id="nin" name="nin" value="<?php echo htmlspecialchars($nin); ?>" maxlength="24" pattern="\d{24}">
                        <?php if (isset($errors['nin'])): ?>
                            <div class="error"><?php echo $errors['nin']; ?></div>
                        <?php endif; ?>
                        <small style="color: #666;">Exactly 24 digits, no spaces</small>
                    </div>
                    
                    <input type="submit" name="submit" value="Register">
                </form>
            </fieldset>
            
            <div style="margin-top: 20px; padding: 15px; background-color: #f5f5f5; border-radius: 5px;">
                <h4>Validation Rules:</h4>
                <ul style="margin-left: 20px; color: #666;">
                    <li>Name: Non-empty string (letters and spaces only)</li>
                    <li>Password: At least 6 characters (must contain at least one letter and one number)</li>
                    <li>NIN: Exactly 24 digits</li>
                </ul>
            </div>
            <?php
        }
        ?>
        
        <div style="text-align: center; margin-top: 20px;">
            <a href="javascript:history.go(0)" class="back-link">↻ Reset Form</a>
        </div>
    </div>
</body>
</html>

Question Six

Use Figure 1 in Question Four to answer the following questions:

i. Write a CSS rule that makes heading level one to be 36 large and color to be red. [3 Marks]

Answer (Click to show)

/* Target the h1 element */
h1 {
    font-size: 36px;
    color: red;
}

Alternative using different units:

h1 {
    font-size: 36pt;  /* Using points */
    color: #FF0000;   /* Hex code for red */
}

If you need to be more specific:

body h1 {
    font-size: 36px;
    color: red;
}

ii. Write a CSS rule that will change the background color of the page to be blue. [3 Marks]

Answer (Click to show)

/* Target the body element */
body {
    background-color: blue;
}

Alternative methods:

/* Using hex code */
body {
    background-color: #0000FF;
}
 
/* Using RGB */
body {
    background-color: rgb(0, 0, 255);
}
 
/* Using universal selector */
* {
    background-color: blue;
}

iii. Write the CSS rule to place the image as a background color of the page. Assume the image is labeled “cive.png”. [3 Marks]

Answer (Click to show)

/* Set image as background */
body {
    background-image: url('cive.png');
}

With additional properties:

body {
    background-image: url('cive.png');
    background-repeat: no-repeat;        /* Don't repeat the image */
    background-position: center;         /* Center the image */
    background-size: cover;              /* Cover the entire page */
    background-attachment: fixed;        /* Fixed background */
}

Shorthand property:

body {
    background: url('cive.png') no-repeat center center fixed;
    background-size: cover;
}

iv. Write a CSS rule to make the background color of the paragraph yellow, arial, bold. [3 Marks]

Answer (Click to show)

/* Target the paragraph with id="parg" */
#parg {
    background-color: yellow;
    font-family: Arial, sans-serif;
    font-weight: bold;
}

If targeting all paragraphs:

p {
    background-color: yellow;
    font-family: Arial, sans-serif;
    font-weight: bold;
}

v. How will the page look after adding the following CSS rule? [3 Marks]

* {
    color: green;
}

Answer (Click to show)
Explanation of * { color: green; }:

The universal selector * selects all elements on the page. Therefore, this rule will set the text color of every element to green.

Effect on the page:

The heading “Welcome to College of Informatics and Virtual Education” will be green

The paragraph text will be green

All list items in both unordered and ordered lists will be green

Even the plain text “For Department of Electronics and Telecommunication Engineering” (which is not wrapped in any tag) will be green because it inherits the color from the body

Any other text on the page will be green

Visual representation:
Welcome to College of Informatics and Virtual Education (green)

For Department of computer science and Engineering (green)
  • BSc.In Computer Science (green)
  • BSc.In Software Engineering (green)

For Department of Electronics and Telecommunication Engineering (green)
  1. BSc.In Telecommunication Engineering (green)
  2. Diploma in Telecommunication (green)
  3. Diploma in Computer Networks (green)
Note: This rule does not affect background colors, borders, or other non-text properties - only the color of text.

vi. Write a CSS rule to change the text color of the ordered list to be green. [5 Marks]

Answer (Click to show)

Method 1: Target the ordered list directly:

ol {
    color: green;
}

Method 2: Target list items within ordered list:

ol li {
    color: green;
}

Method 3: Using class or ID (if assigned):

/* If the ol had an id like <ol id="programs-list"> */
#programs-list {
    color: green;
}
 
/* or with class */
.programs {
    color: green;
}

Method 4: More specific selector:

body ol {
    color: green;
}

Complete CSS with additional styling:

/* Style the ordered list */
ol {
    color: green;
    font-weight: bold;
    list-style-type: decimal;  /* Ensure numbers are displayed */
}
 
/* Style only the list items within ordered list */
ol li {
    color: green;
    margin-bottom: 5px;
}
 
/* Different color for different levels (if nested) */
ol li {
    color: green;
}
 
ol ol li {
    color: lightgreen;  /* Nested lists get lighter green */
}

Question Seven

The following question use a database CS0219, table called users with the following structure: Assume the table already has some data inside.

CREATE TABLE users (
    RegNo VARCHAR(20) NOT NULL PRIMARY KEY,
    FirstName VARCHAR(20) NOT NULL,
    LastName VARCHAR(20) NOT NULL,
    Surname VARCHAR(20)
);

i. Write a code to make connection between PHP and Database. Servername=127.0.0.1, User=root, password="". [4 Marks]

Answer (Click to show)

Method 1: MySQLi (Object-Oriented)

<?php
// Database connection parameters
$servername = "127.0.0.1";
$username = "root";
$password = "";
$database = "CS0219";
 
// Create connection
$conn = new mysqli($servername, $username, $password, $database);
 
// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}
echo "Connected successfully";
?>

Method 2: MySQLi (Procedural)

<?php
$conn = mysqli_connect("127.0.0.1", "root", "", "CS0219");
 
if (!$conn) {
    die("Connection failed: " . mysqli_connect_error());
}
echo "Connected successfully";
?>

Method 3: PDO (PHP Data Objects)

<?php
try {
    $conn = new PDO("mysql:host=127.0.0.1;dbname=CS0219", "root", "");
    // Set PDO error mode to exception
    $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    echo "Connected successfully";
} catch(PDOException $e) {
    echo "Connection failed: " . $e->getMessage();
}
?>

Complete connection script with error handling:

<?php
// config.php
$servername = "127.0.0.1";
$username = "root";
$password = "";
$dbname = "CS0219";
 
// Create connection
$conn = new mysqli($servername, $username, $password, $dbname);
 
// Check connection
if ($conn->connect_error) {
    error_log("Connection failed: " . $conn->connect_error);
    die("Database connection error. Please try again later.");
}
 
// Set charset to UTF-8
$conn->set_charset("utf8");
 
// echo "Connected successfully"; // Comment out in production
?>

ii. Write a PHP code to insert your details to the database (Your RegNo, first name, last name and surname). [4 Marks]

Answer (Click to show)

<?php
// Include database connection
require_once 'config.php'; // Assuming connection code is in config.php
 
// Your personal details
$regNo = "CS/123/2020";  // Replace with your actual registration number
$firstName = "John";      // Replace with your first name
$lastName = "Doe";        // Replace with your last name
$surname = "Smith";       // Replace with your surname
 
// Method 1: Using MySQLi (Object-Oriented) with prepared statement (Recommended)
$stmt = $conn->prepare("INSERT INTO users (RegNo, FirstName, LastName, Surname) VALUES (?, ?, ?, ?)");
$stmt->bind_param("ssss", $regNo, $firstName, $lastName, $surname);
 
if ($stmt->execute()) {
    echo "New record created successfully. RegNo: " . $regNo;
} else {
    echo "Error: " . $stmt->error;
}
 
$stmt->close();
 
// Method 2: Using MySQLi (Object-Oriented) without prepared statement
/*
$sql = "INSERT INTO users (RegNo, FirstName, LastName, Surname) 
        VALUES ('$regNo', '$firstName', '$lastName', '$surname')";
 
if ($conn->query($sql) === TRUE) {
    echo "New record created successfully";
} else {
    echo "Error: " . $sql . "<br>" . $conn->error;
}
*/
 
// Method 3: Using PDO
/*
try {
    $sql = "INSERT INTO users (RegNo, FirstName, LastName, Surname) 
            VALUES (:regNo, :firstName, :lastName, :surname)";
    $stmt = $conn->prepare($sql);
    $stmt->execute([
        ':regNo' => $regNo,
        ':firstName' => $firstName,
        ':lastName' => $lastName,
        ':surname' => $surname
    ]);
    echo "New record created successfully";
} catch(PDOException $e) {
    echo "Error: " . $e->getMessage();
}
*/
 
// Close connection
$conn->close();
?>

iii. Write a PHP code to retrieve all users in the database and display their details on the browser. [6 Marks]

Answer (Click to show)

<?php
// Include database connection
require_once 'config.php';
?>
 
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Users List - CS0219 Database</title>
    <style>
        * {
            box-sizing: border-box;
            margin: 0;
            padding: 0;
        }
        
        body {
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            min-height: 100vh;
            padding: 20px;
        }
        
        .container {
            max-width: 1000px;
            margin: 0 auto;
            background-color: white;
            border-radius: 15px;
            padding: 30px;
            box-shadow: 0 10px 30px rgba(0,0,0,0.2);
        }
        
        h1 {
            color: #333;
            margin-bottom: 20px;
            text-align: center;
        }
        
        h1 span {
            color: #667eea;
        }
        
        .table-container {
            overflow-x: auto;
            border-radius: 10px;
            box-shadow: 0 5px 15px rgba(0,0,0,0.1);
        }
        
        table {
            width: 100%;
            border-collapse: collapse;
            background-color: white;
        }
        
        th {
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            color: white;
            font-weight: 600;
            padding: 15px;
            text-align: left;
            font-size: 14px;
            text-transform: uppercase;
            letter-spacing: 0.5px;
        }
        
        td {
            padding: 12px 15px;
            border-bottom: 1px solid #e0e0e0;
            color: #555;
        }
        
        tr:hover {
            background-color: #f8f9fa;
        }
        
        .stats {
            background-color: #f8f9fa;
            padding: 15px;
            border-radius: 10px;
            margin-bottom: 20px;
            text-align: center;
            font-size: 16px;
        }
        
        .badge {
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            color: white;
            padding: 5px 15px;
            border-radius: 20px;
            font-size: 14px;
        }
        
        .no-data {
            text-align: center;
            padding: 40px;
            color: #999;
            font-style: italic;
        }
        
        .footer {
            margin-top: 20px;
            text-align: center;
            color: #666;
            font-size: 12px;
        }
    </style>
</head>
<body>
    <div class="container">
        <h1>CS0219 <span>Users Database</span></h1>
        
        <?php
        // Method 1: Using MySQLi (Object-Oriented)
        $sql = "SELECT RegNo, FirstName, LastName, Surname FROM users ORDER BY RegNo";
        $result = $conn->query($sql);
        
        // Display statistics
        if ($result) {
            $totalUsers = $result->num_rows;
            echo "<div class='stats'>";
            echo "<span class='badge'>Total Users: " . $totalUsers . "</span>";
            echo "</div>";
        }
        
        // Check if there are results
        if ($result && $result->num_rows > 0) {
            echo "<div class='table-container'>";
            echo "<table>";
            echo "<thead>";
            echo "<tr>";
            echo "<th>Reg No</th>";
            echo "<th>First Name</th>";
            echo "<th>Last Name</th>";
            echo "<th>Surname</th>";
            echo "</tr>";
            echo "</thead>";
            echo "<tbody>";
            
            // Output data of each row
            while($row = $result->fetch_assoc()) {
                echo "<tr>";
                echo "<td><strong>" . htmlspecialchars($row['RegNo']) . "</strong></td>";
                echo "<td>" . htmlspecialchars($row['FirstName']) . "</td>";
                echo "<td>" . htmlspecialchars($row['LastName']) . "</td>";
                echo "<td>" . htmlspecialchars($row['Surname'] ?? 'N/A') . "</td>";
                echo "</tr>";
            }
            
            echo "</tbody>";
            echo "</table>";
            echo "</div>";
        } else {
            echo "<div class='no-data'>";
            echo "No users found in the database.";
            echo "</div>";
        }
        
        // Method 2: Alternative using while loop with fetch_array
        /*
        echo "<h3>Alternative Display Method:</h3>";
        $result = $conn->query($sql);
        if ($result->num_rows > 0) {
            echo "<ul>";
            while($row = $result->fetch_array(MYSQLI_ASSOC)) {
                echo "<li>" . $row['RegNo'] . " - " . $row['FirstName'] . " " . $row['LastName'] . "</li>";
            }
            echo "</ul>";
        }
        */
        
        // Method 3: Using PDO
        /*
        try {
            $stmt = $conn->query("SELECT RegNo, FirstName, LastName, Surname FROM users");
            $users = $stmt->fetchAll(PDO::FETCH_ASSOC);
            
            if (count($users) > 0) {
                echo "<table>";
                echo "<tr><th>RegNo</th><th>FirstName</th><th>LastName</th><th>Surname</th></tr>";
                foreach($users as $row) {
                    echo "<tr>";
                    echo "<td>" . htmlspecialchars($row['RegNo']) . "</td>";
                    echo "<td>" . htmlspecialchars($row['FirstName']) . "</td>";
                    echo "<td>" . htmlspecialchars($row['LastName']) . "</td>";
                    echo "<td>" . htmlspecialchars($row['Surname'] ?? 'N/A') . "</td>";
                    echo "</tr>";
                }
                echo "</table>";
            } else {
                echo "0 results";
            }
        } catch(PDOException $e) {
            echo "Error: " . $e->getMessage();
        }
        */
        
        // Close connection
        $conn->close();
        ?>
        
        <div class="footer">
            <p>© 2020 College of Informatics and Virtual Education - University of Dodoma</p>
            <p>Database: CS0219 | Table: users</p>
        </div>
    </div>
</body>
</html>

iv. What is the importance of the Primary Key in the users table? [3 Marks]

Answer (Click to show)
Importance of Primary Key in the users table:

Uniqueness: Ensures each record (student) has a unique RegNo, preventing duplicate entries.

Fast Data Retrieval: Primary keys are automatically indexed, making searches by RegNo very fast.

Data Integrity: Prevents insertion of NULL or duplicate values in the RegNo field.

Relationship Building: Enables linking to other tables (e.g., courses, grades) through foreign keys.

Automatic Sorting: Data is typically stored in primary key order for efficient access.

Record Identification: Provides a reliable way to identify, update, or delete specific students.

Constraint Enforcement: Enforces entity integrity by ensuring every row is uniquely identifiable.

Example of primary key benefits:
-- Fast lookup by RegNo
SELECT * FROM users WHERE RegNo = 'CS/123/2020'; -- Very fast due to primary key index
 
-- This would fail because RegNo must be unique
INSERT INTO users (RegNo, FirstName) VALUES ('CS/123/2020', 'Another'); -- Error!

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IP2 (CP 311) UE 2019-2020 SOLVED NON DEGREE

THE UNIVERSITY OF DODOMA

COLLEGE OF INFORMATICS AND VIRTUAL EDUCATION

DEPARTMENT OF COMPUTER SCIENCE AND ENGINEERING

NON-DEGREE UNIVERSITY EXAMINATIONS

FIRST SEMESTER 2019/2020

INSTRUCTIONS:

SECTION A: (60 Marks)

Question One

Question Two

Question Three

Question Four

SECTION B (40 Marks)

Attempt ANY TWO questions from this section.

Question Five

Question Six

Question Seven

END OF EXAMINATION PAPER

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