title: How to use two columns in a foreign key constraint
body: <p>I have two tables:</p>
  
  <ol>
  <li><code>Article</code></li>
  <li><code>Subscription</code></li>
  </ol>
  
  <p>In the <code>Article</code> table I have two columns that make up the primary key: <code>id</code>, <code>sl</code>. In the <code>Subscription</code> table I have a foreign key 'idsl`.</p>
  
  <p>I use this constraint :</p>
  
  <pre><code>constraint FK_idsl 
    foreign key (idsl) references CSS_SubscriptionGroup(id, sl)
  </code></pre>
  
  <p>But when I run the query, I getting this error:</p>
  
  <blockquote>
    <p>Number of referencing columns in foreign key differs from number of referenced columns, table X</p>
  </blockquote>