uploaded image to post

Hi,

i have a front-end form, to create new post, and in where files can be ‘attached’.
Once a file is ‘selected’ it will be uploaded directly. And the attachment_id is saved in the form.

Once the whole form is submitted, the post is created, and i have the post_id.

but can i link the attachment to the post?

i cant seem to find any function for this.
“wp_insert_attachment” does the only job. But i have already uploaded the file. so i can not use this function.

// brain-fart….
Or should i just use an sql-statement for this?