title: Primary key not AUTO INCREMENT in the PostgreSQL
body: <p>I have table Category and I  have 3 columns <code>category_id, category_name,category_description</code>.
  When I execute insert script without <code>category_id</code> parameter I have this error:</p>
  
  <pre><code>ERROR:  null value in column "category_id" violates not-null constraint
  DETAIL:  Failing row contains (null, T_601, Yojimbo).
  SQL state: 23502
  </code></pre>
  
  <p>This is my select script:</p>
  
  <pre><code>INSERT INTO category ( category_name, category_description)
      VALUES ('T_601', 'Yojimbo');
  </code></pre>
  
  <p>This is the image of my table : 
  <a href="https://i.stack.imgur.com/Y830A.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Y830A.png" alt="t"></a></p>