Use PHP's sprintf() function to enhance the security of SQL operations

When writing PHP applications, interacting with databases is a very common task. However, if user input is not handled correctly, it can lead to security vulnerabilities, such as SQL injection attacks. Fortunately, PHP provides some built-in functions to help us write safer SQL queries, including the sprintf() function.

The sprintf() function is a powerful string formatting function in PHP, which allows us to create strings according to the specified format. We can use this function to build secure SQL queries, ensuring that user input is properly escaped and quoted, thereby preventing SQL injection attacks.

Here is an example that demonstrates how to use the sprintf() function to build a safe SQL query:

// 假设以下变量是用户提供的输入
$userId = $_POST['user_id'];
$userName = $_POST[