What does $stmt in php mean?

$stmt in PHP is a variable name representing a prepared statement object. When using prepared statements, you first need to prepare a statement object by calling the prepare() method of the PDO class. This statement object can contain one or more placeholders, and then these placeholders are replaced with actual values ​​before executing the query.

Operating system for this tutorial: Windows 10 system, php8.1.3 version, Dell G3 computer.

In PHP, $stmt is a variable name representing a prepared statement object.

Prepared statements are a technique used to execute the same query or command multiple times, which can improve database execution speed and security, and prevent SQL injection attacks.

When using prepared statements, you first need to prepare a statement object by calling the prepare() method of the PDO class. This statement object can contain one or more placeholders, which need to be replaced with actual values ​​before the query is executed.

For example:

$sql = "SELECT * FROM users WHERE username = :username";
$stmt = $pdo->prepare($sql);
$stmt->bindParam(':username', $username);
$stmt->execute();

In the above code, the variable stmt is a statement object, which contains a query statement with placeholders. Before executing the query, we use the bindParam() method to bind the placeholder: username to the variable username, and then call the execute() method to execute the query.

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