How does the concept of escaping values apply to different types of SQL queries in PHP, such as SELECT, INSERT, and DELETE?

When working with SQL queries in PHP, it is essential to escape values to prevent SQL injection attacks. This means sanitizing user input before including it in a query to ensure that malicious code cannot be executed. This applies to all types of SQL queries, including SELECT, INSERT, and DELETE, to maintain the security of the application. 

// Example of escaping values in a SELECT query
$userInput = $_POST['input'];
$escapedInput = mysqli_real_escape_string($connection, $userInput);

$query = "SELECT * FROM table WHERE column = '$escapedInput'";
$result = mysqli_query($connection, $query);

// Example of escaping values in an INSERT query
$userInput = $_POST['input'];
$escapedInput = mysqli_real_escape_string($connection, $userInput);

$query = "INSERT INTO table (column) VALUES ('$escapedInput')";
mysqli_query($connection, $query);

// Example of escaping values in a DELETE query
$userInput = $_POST['input'];
$escapedInput = mysqli_real_escape_string($connection, $userInput);

$query = "DELETE FROM table WHERE column = '$escapedInput'";
mysqli_query($connection, $query);

Keywords

SQL injection mysqli_real_escape_string prepared statements PDO data sanitization

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