Is primary key only one column?

Can a primary key be two columns?

A table can have only ONE primary key; and in the table, this primary key can consist of single or multiple columns (fields).

How many columns can a primary key have?

In both these examples, primary key contains only one column. In the case of Books table, it is the BookId column and in the case of Authors , it is AuthorId .

Is the primary key of one table?

Primary Key Constraints A table typically has a column or combination of columns that contain values that uniquely identify each row in the table. This column, or columns, is called the primary key (PK) of the table and enforces the entity integrity of the table.

Is primary key only one attribute?

A primary key is a logical constraint comprised of a collection of attributes that uniquely identify the members of a set; that collection can have only one member.