we have to declare Primary key in one particular column like id column???

Question

if I didn't declare any primary column then sql itself declare one column or not???

Answer 1

I don't think it is compulsory to have a primary key in SQL but is is recommended. Every table should have a unique identification which is provided by primary key. Table rows without unique identification in system is not a good practice.

Answer 2

I'd say it's more than recommended usage of 'primary key' when dealing with database. Sometimes you might get identical results in your database, so better to always use it. It just takes couple of seconds to select it when creating columns, so yeah you should use it.