How to save files to the database in the order in which the user chooses them

I have no idea how to save files to a database in order that user chooses them in the input tag. I would to add sortable functionality to it with Jquery. In a database, I have a table files, that has id as a foreign key. The foreign key is used to connect to a post table. Thank you in advance for your answers.

I try to create a column in a database with position of a file, but it did not work out.