how to correlate values?
<p>I have 10 sets of 3 values. At each point, I will only know 1 of the values and need to retrieve the other 2 values. For example, I know what id_a2 is, how do I use that to get id_a1 and id_a3?</p>

<pre><code>id_a1, id_a2, id_a3
id_b1, id_b2, id_b3
id_c1, id_c2, id_c3...
</code></pre>
