01

The PRIMARY KEY can be created on the same line when declaring a column,

CREATE TABLE student(
    student_id INT PRIMARY KEY,
    name VARCHAR(20),
    major VARCHAR(20)
);
    

We use the PRIMARY KEY to reference the table

02

Or, We can place the column we want inside the PRIMARY KEY() function

CREATE TABLE student(
    student_id INT,
    name VARCHAR(20),
    major VARCHAR(20),
    PRIMARY KEY (student_id)
);
DESCRIBE student