A unique ID for a poll response
<p>In my system a manager create a poll and publish it to the world so users which have the link to the poll can answer it.</p>

<p>There is some question which designed to receive multiple answers, so user can choose multiple distract in one response.</p>

<p><strong>The response table structure in the DB</strong></p>

<ul>
<li>ID</li>
<li>ActivityID - the poll ID</li>
<li>Value - the district value</li>
<li>TimeResponse</li>
</ul>

<p>In the database i am currently saving each response separately.</p>

<p>I will give you an example
Lets say there is 4 district in a poll (a,b,c,d)
User choose the following district (a,b,c)</p>

<p>The response table will look like this:</p>

<pre><code>   ID       ActivityID      Value    TimeResponse
    1           234            a        01/01/2012 
    2           234            b        01/01/2012
    3           234            c        01/01/2012
</code></pre>

<p>So if i try to count the ID i will get the number 3 which represent the number of district were answered is a given poll.</p>

<p>BUT i need the number of responses per user in a given poll, so i need somehow to combine those two...</p>

<p>Until now i thought about the following solutions but neither of them is good.</p>

<ul>
<li>the first solution was to add a column of the user's IP, but sometimes i cant get the user's IP.</li>
<li>the second solution was to add a column of the user's sessionID using the sessionIDManager, but if the user answer twice (2 response) it will store the same session ID.</li>
</ul>

<p>FYI, the user which answer the poll is anonymous. </p>

<p>And also one of the system requirement is to allow a user to answer a poll several times </p>
