In SQL, is it a must I indicate a primary key? Can't my first column which has int as datatype be the primary key by default?

Question

Database

Answer 1

Yes, pk is required. But pk is a combination of NOT NULL and UNIQUE. So a email address can be a pk, too. Check the sl course for the full sytax of relation declaration.

Answer 2

You're welcome

CREATE TABLE Users
(
UserID int,
FirstName varchar(100),
LastName varchar(100),
City varchar(100),
PRIMARY KEY(UserID)
);

Answer 3

Thanks