How can debugging techniques be applied to identify and resolve issues with data retrieval and display in PHP?

Issue: One common issue with data retrieval and display in PHP is incorrect SQL queries or database connection errors. To identify and resolve these issues, you can use debugging techniques like printing out the SQL queries, checking for errors in database connection, and using functions like mysqli_error() to get detailed error messages. PHP Code Snippet: 

// Establish a database connection
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "database";

$conn = new mysqli($servername, $username, $password, $dbname);

// Check for connection errors
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}

// Example SQL query
$sql = "SELECT * FROM users";

// Print out the SQL query for debugging
echo "SQL Query: " . $sql . "<br>";

// Execute the SQL query
$result = $conn->query($sql);

// Check for errors in the query execution
if (!$result) {
    die("Query failed: " . $conn->error);
}

// Display the retrieved data
while ($row = $result->fetch_assoc()) {
    echo "User ID: " . $row["id"] . " - Name: " . $row["name"] . "<br>";
}

// Close the database connection
$conn->close();

Keywords

Xdebug var_dump error_reporting PHP errors display_errors

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