What are the main functions used in the PHP code provided in the forum thread?

The main functions used in the PHP code provided in the forum thread are `mysqli_connect`, `mysqli_query`, and `mysqli_fetch_assoc`. These functions are used to establish a connection to the database, execute a query, and fetch the results as an associative array, respectively. To fix the issue, ensure that the database connection details are correct and that the query being executed is valid. Additionally, make sure to handle any errors that may occur during the database operations.

// Establish a connection to the database
$connection = mysqli_connect("localhost", "username", "password", "database");

// Check if the connection was successful
if (!$connection) {
    die("Connection failed: " . mysqli_connect_error());
}

// Execute a query
$query = "SELECT * FROM table_name";
$result = mysqli_query($connection, $query);

// Fetch the results as an associative array
while ($row = mysqli_fetch_assoc($result)) {
    // Process the data
}

// Close the connection
mysqli_close($connection);