How can one prevent fields from being emptied in a database record when updating user profiles using PHP?

When updating user profiles in a database using PHP, one can prevent fields from being emptied by first fetching the existing user data, merging it with the new data, and then updating the database record with the merged data. This way, only fields that have been updated will be changed, while the rest will remain the same.

// Fetch existing user data
$existingData = fetchUserDataFromDatabase($userId);

// Merge existing data with new data
$mergedData = array_merge($existingData, $_POST);

// Update database record with merged data
updateUserInDatabase($userId, $mergedData);