What's the meaning of RESTRICT in Foreign Keys?
<p>There is 4 cases: <em>(For example I'm talking about <code>ON DELETE</code>)</em></p>

<ul>
<li><strong><code>CASCADE</code></strong>: the referencing rows will be deleted automatically along with the referenced ones.</li>
<li><strong><code>SET NULL</code></strong>: the value of referencing record will be set to <code>NULL</code> automatically along with the referenced ones.</li>
<li><strong><code>NO ACTION</code></strong>: There will not be any change in the the referencing rows when the referenced ones are deleted.</li>
<li><strong><code>RESTRICT</code></strong>: { I cannot understand its concept }</li>
</ul>

<p>I read the <a href="http://dev.mysql.com/doc/refman/5.5/en/innodb-foreign-key-constraints.html" rel="nofollow">documentation</a> several times for that, but still I cannot understand what <code>RESTRICT</code> does. May you please someone explain it by an example?</p>

<p>I read somewhere <code>NO ACTION</code> and <code>RESTRICT</code> are the same in MySQL. Is that true?</p>