A prepared statement in PHP is a way to execute a database query that includes placeholders for input values, rather than embedding input values directly into the query string. Prepared statements are a powerful tool for preventing SQL injection attacks, improving query performance, and making code more maintainable.
The process of using a prepared statement involves two steps:
- Prepare: The first step is to prepare the query by creating a statement object with placeholders for input values. This statement object can be created using the
prepare()method of a PDO or MySQLi object. For example, in PDO, you would create a prepared statement like this:
$stmt = $pdo->prepare('SELECT * FROM users WHERE username = :username');
- Bind and execute: The second step is to bind input values to the placeholders in the prepared statement and execute the statement. Input values can be bound to placeholders using the
bindValue()method of the statement object. For example, in PDO, you would bind input values like this:
$username = 'john.doe'; $stmt->bindParam(':username', $username); $stmt->execute();
When the statement is executed, the database engine will use the prepared statement to generate a query that includes the input values. By using a prepared statement, you can ensure that input values are properly escaped and prevent SQL injection attacks.
Prepared statements can also improve query performance, particularly if you need to execute the same query multiple times with different input values. By preparing the statement once and binding different input values to the placeholders, you can avoid the overhead of parsing and optimizing the query each time it is executed.
Overall, prepared statements are an important tool for writing secure, efficient, and maintainable database code in PHP.