如果函数使用php来创建一个isset，以避免并更新MYSQL更新的输入是否为空

Hi I am newish to php and I have created an update page for Content Management System. I have a file upload in this case a picture. I have other inputs that contain text and I can get them to populate my form and thats fine and works great because the user can see what has already been entered. But the file name for the photo can not have a value so if the user doesn't pick the picture from the directory again it will update minus the picture. Hi I am newish to php and I have created an upd