Regexp_like check for symbol in string
<p>If I want to check that string contains <code>@</code>symbol I can write something like</p>

<pre><code>REGEXP_LIKE(source_column,'@')
</code></pre>

<p>or</p>

<pre><code>REGEXP_LIKE(source_column, '.*@.*')
</code></pre>

<p>What is the difference between these two forms? 
And why <code>REGEXP_LIKE(source_column,'@')</code> returns true even if string has other symbols than <code>@</code>? For example it matches with <code>mail@mail.com</code> and <code>12@</code> </p>

<p>Naturally <code>'@'</code> looks like <strong>exact</strong> string match for me, and <code>'.*@.*'</code> I read as 'any string with that symbol'.</p>