hi ive followed a w3 schools form works fine for submission but if i refresh browers i get the following error

Error: INSERT INTO userprofile (postcode, town, firstname, pfirstname, sexuality, psexuality, height, pheight, bodytype, pbodytype, tattoos, ptattoos, piercings, ppiercings, drinking, pdrinking, race, prace, smoker, psmoker) VALUES ('', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '')
Duplicate entry '0' for key 'PRIMARY'

Iced turned autocomplete off but the form is still being auto completed as soon as i refresh page or if i shut page down or restart browser like this


what could it be thats causing this