Prepared statements are a powerful feature in PHP for executing SQL queries securely and efficiently. They provide a way to separate SQL logic from data, enhancing both security and performance.

What are Prepared Statements?

Prepared statements are precompiled SQL queries that allow you to execute the same statement repeatedly with high efficiency. They act as templates for similar SQL statements, accepting parameters to customize each execution.

Benefits of Using Prepared Statements

Protection against SQL injection attacks
Improved query performance for repeated executions
Cleaner and more readable code
Automatic escaping of special characters

Basic Syntax

Here's a simple example of how to use prepared statements in PHP with MySQLi:


$stmt = $mysqli->prepare("INSERT INTO users (name, email) VALUES (?, ?)");
$stmt->bind_param("ss", $name, $email);

$name = "John Doe";
$email = "john@example.com";
$stmt->execute();

Step-by-Step Process

Prepare the statement using placeholders (?) for values
Bind parameters to the placeholders
Execute the statement

Parameter Binding

The bind_param() function is used to associate variables with the placeholders. The first argument specifies the data types of the parameters:

"i" - integer
"d" - double
"s" - string
"b" - blob

Advanced Example: SELECT Query

Here's a more complex example using a SELECT query with prepared statements:


$stmt = $mysqli->prepare("SELECT name, email FROM users WHERE id > ? AND status = ?");
$stmt->bind_param("is", $id, $status);

$id = 100;
$status = "active";

$stmt->execute();
$result = $stmt->get_result();

while ($row = $result->fetch_assoc()) {
    echo $row['name'] . " - " . $row['email'] . "\n";
}

Best Practices

Always use prepared statements for queries involving user input
Close prepared statements after use to free up resources
Use meaningful variable names for better code readability
Handle errors appropriately using try-catch blocks or error checking

Related Concepts

To further enhance your PHP database skills, explore these related topics:

Conclusion

Prepared statements are an essential tool for secure and efficient database interactions in PHP. By separating SQL logic from data and automatically handling parameter escaping, they significantly reduce the risk of SQL injection attacks while improving query performance.