y to do it</li>
</ul></li>
<li>There are similar issues with deleting rows through a view
<ul>
<li>it is possible in some cases, but not all</li>
</ul></li>
</ul>
<h2 id="constraints">Constraints</h2>
<ul>
<li>Constraints can be defined in <code>create table</code> statements</li>
<li>Or added to existing tables with <code>alter table</code> statements</li>
<li>Different types of constraints
<ul>
<li>Null or not null</li>
<li>Primary key</li>
<li>Unique</li>
<li>Foreign key</li>
<li>Check</li>
<li>Domain</l