cannot insert data into mysql

When I am going to create a new product Item into my depot application I got the following error:

Mysql::Error: #23000Duplicate entry '0' for key 1: INSERT INTO products (`image_url`, `date_available`, `price`, `title`, `description`) VALUES('[](', '2010-08-27 12:23:00', '90.0', 'jjhjh', 'hgjgjhjkhjhkhkkkkkhkhkhkh')

I am new to ruby on rails and following Agile Web Development with Rails.

Please help me about the problem.

the id is not auto-increment but unique

yap I have solved that problem it was not set to auto increment. Thanks dear:)