How can you troubleshoot and debug issues with querying a database in PHP?

When troubleshooting and debugging database querying issues in PHP, you can start by checking the connection to the database, ensuring that the query syntax is correct, and verifying that the data being retrieved matches your expectations. Utilizing error handling techniques, such as try-catch blocks and error reporting, can also help identify and resolve any issues that may arise. 

// Example PHP code snippet for troubleshooting and debugging database querying issues

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

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

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

// Query the database
$sql = "SELECT * FROM table";
$result = $conn->query($sql);

// Check if the query was successful
if ($result === false) {
    echo "Error: " . $conn->error;
} else {
    // Process the retrieved data
    while ($row = $result->fetch_assoc()) {
        echo "Column1: " . $row["column1"] . " - Column2: " . $row["column2"] . "<br>";
    }
}

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

Keywords

SQL injection PDO error handling debugging query optimization

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