How can PHP beginners avoid errors when defining and executing SQL queries in their code?

PHP beginners can avoid errors when defining and executing SQL queries in their code by using prepared statements with parameterized queries. This approach helps prevent SQL injection attacks and ensures proper data sanitization. By separating the SQL query from the user input, beginners can write safer and more secure code. 

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

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

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

// Define a SQL query with a parameter
$sql = "SELECT * FROM users WHERE username = ?";

// Prepare the statement
$stmt = $conn->prepare($sql);

// Bind parameters
$stmt->bind_param("s", $username);

// Set parameter values
$username = "john_doe";

// Execute the statement
$stmt->execute();

// Get the result
$result = $stmt->get_result();

// Display the results
while ($row = $result->fetch_assoc()) {
    echo "Username: " . $row['username'] . "<br>";
}

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

Keywords

SQL injection prepared statements PDO mysqli error handling

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