Question

What do you understand by primary key ? How will you define a primary key for a table ?

Answer 1

the candidate key that one chooses to identify each record of a table uniquely is called the primary key

in the vehicle table, if you choose 'serial number'to identify each round uniquely then it will be the primary key for a table

Answer 2

Answer:

A primary key is a field in a table which uniquely identifies each row/record in a database table. A primary key column cannot have NULL values. A table can have only one primary key, which may consist of single or multiple fields. When multiple fields are used as a primary key, they are called a composite key.