y keys, but for candidate (secondary) keys</li>
<li>Defined in the same way, but with <code>unique</code> instead of <code>primary key</code></li>
<li><em>Example</em>:
<ul>
<li>adding a <code>unique</code> constraint to the <code>code</code> column of the <code>course</code> table</li>
</ul></li>
</ul>
<div class="sourceCode" id="cb10"><pre class="sourceCode sql"><code class="sourceCode sql"><span id="cb10-1"><a href="#cb10-1" aria-hidden="true"></a><span class="kw">set</span> search_path <span class="kw">