PRIMARY KEY definition in MySQL CREATE TABLE statement

Question

What\'s the difference between this code:

CREATE TABLE samples (
  sampleid INT(11) NOT NULL AUTO_INCREMENT,
  sampledate DATE NOT NULL,
  location VARCHAR(25) N         


        

Answer 1

The way I see it is.. The first method is used to create composite keys. While the second method (more readable to me) is primarily used if there is only primary key in the table.

The second method cannot be used if you want to implement composite key