title: What is the use of CONSTRAINT keyword when adding a Foreign key?
body: <p>I Can't figure out what is the difference between these two.</p>
  
  <pre><code>CONSTRAINT fk_PerOrders FOREIGN KEY (P_Id) REFERENCES ..
  </code></pre>
  
  <p>and</p>
  
  <pre><code>FOREIGN KEY (P_Id) REFERENCES ..
  </code></pre>
  
  <p>Is it just naming, or something else?</p>