Error 1062 duplicate entry '0' for key 'primary'

Question

can't add primary key for ID table and how to fix it?

https://i.sstatic.net/Mj4I0.png

Answer 1

It seems as though you have multiple rows in the table that have id = 0.

In order to add the primary key to the table you'll need to either delete those duplicate rows or update their id fields to be a unique value.