title: LinQ with Count and Where condition
body: <p>Hihi, I have a table with the following data:</p>
  
  <pre><code>    SampleID | SampleKey | SampleData
      1        | 1         | abc
      1        | 2         | def
      2        | 1         | xxx
      2        | 3         | yyy
      3        | 3         | zzz
      3        | 4         | qqq
  </code></pre>
  
  <p>I would like to retrieve all rows with at least one SampleKey as 3, which should give me</p>
  
  <pre><code>    2        | 1         | xxx
      2        | 3         | yyy
      3        | 3         | zzz
      3        | 4         | qqq       
  </code></pre>
  
  <p>both SampleID with 2 and 3 should be returned as they are considered as one pair.</p>
  
  <p>Pls advice how can I achieve this? May thanks!</p>