SQL Primary Key
I came across the 2 versions of sql code..  

    --1
    CREATE TABLE Location ( 
	Id     INTEGER PRIMARY KEY 
                       NOT NULL,
	Name   TEXT    NOT NULL 
    );
    
    --2
    CREATE TABLE Location ( 
    	Id     INTEGER PRIMARY KEY 
                           NOT NULL
                           UNIQUE,
    	Name   TEXT    NOT NULL 
    );


In TSQL, is it necessary to specify the primary key to be unique and not null?  
I always assumed that the primary key was unique and could not be null. 
SQL Primary Key
===

I came across the 2 versions of sql code..  

    --1
    CREATE TABLE Location ( 
	Id     INTEGER PRIMARY KEY 
                       NOT NULL,
	Name   TEXT    NOT NULL 
    );
    
    --2
    CREATE TABLE Location ( 
    	Id     INTEGER PRIMARY KEY 
                           NOT NULL
                           UNIQUE,
    	Name   TEXT    NOT NULL 
    );


In TSQL, is it necessary to specify the primary key to be unique and not null?  
I always assumed that the primary key was unique and could not be null. 