Reserve id in Mysql how?

Question

MySQL

There is an activity where a form for filling in ad parameters such as title, photos, etc. When choosing a photo, I want the photo to be immediately saved to the server and the activity receives a link to the uploaded image, and when you click on the "create ad" button, the fields are filled with the rest of the data. How is it done correctly?
For example, a user has uploaded the first photo - a record for a future announcement has been created on the server. And if he did not click then "create ad", then an empty string is obtained. Who knows?

Answer 1

upload a photo, get its id in the response and insert it into some hidden attribute of the form. When sending an ad, you immediately send them with identifiers. Empty lines will only litter your database