-- primary key
-- The PRIMARY KEY constraint uniquely identifies each record in a table.
-- Primary keys must contain UNIQUE values, and cannot contain NULL values.
-- A table can have only ONE primary key
create table Person(PersonID int Primary key, LastName varchar(255),FirstName varchar(255), Age int);
insert into Person(PersonID, LastName, FirstName, Age)values(1, "Hansen","Ola",30);
insert into Person(PersonID, LastName, FirstName, Age)values(2,"Svedson","Tov",23);
insert into Person(PersonID, LastName, FirstName, Age)values(3,"Zenitsu","YellowStone",20);
select * from Person;