Why are my form values not being inserted into my MySQL database?

PHP: Inserting Values from the Form into MySQL

Inserting values from a form into a MySQL database is a common task for web development. In PHP, you can use the mysqli extension to connect to the database and execute queries.

However, if you are facing issues where values are not being inserted into the database, it's important to consider the following:

Declared but Unexecuted Query:

$sql = "INSERT INTO users (username, password, email)
VALUES ('".$_POST["username"]."','".$_POST["password"]."','".$_POST["email"]."')";

This code only declares a string variable containing the MySQL query. To execute the query, you need to use functions like mysqli_query or prepare a statement using mysqli_prepare, mysqli_bind_param, and mysqli_execute.

SQL Injection Vulnerability:

Never append user input directly to your query. It can lead to SQL injection attacks, where users can manipulate input to cause damage to your database. Instead, use prepared statements to protect against this vulnerability.

Prepared Statement Example:

$sql = "INSERT INTO users (username, password, email)
VALUES (?,?,?)";

$stmt = $mysqli->prepare($sql);
$stmt->bind_param("sss", $_POST['username'], $_POST['email'], $_POST['password']);
$stmt->execute();

Security Considerations:

• Do not store passwords in clear text. Use password_hash to store a hash of the password.

Remember, user input should always be treated with caution, and security measures like prepared statements should be implemented to prevent vulnerabilities.

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