How can PHP be used to ensure that certain fields, like passwords, are only updated if they are filled out in a form?

To ensure that certain fields, like passwords, are only updated if they are filled out in a form, you can use conditional statements in PHP to check if the field is empty or not before updating the database. This can help prevent accidentally overriding existing data with empty values.

if(!empty($_POST['password'])){
    // Update password in the database
}