title: What is the optimum way to design this simple table with 3 unique columns in this case?
body: <p>Say, I got a table with 3 columns (varchar type), the Unique key= the combination of the 3 columns.
  Should I create 1 more column (int type) &amp; set the primary key for it, of course we still set the unique (column1, column2, column3)?</p>
  
  <p>So which one is better? 3 unique columns or 4 columns (1 primary key + 3 unique columns)
  and why you think that option is better?</p>