title: SQL Number of Occurrences, summary Query
body: <p>I have a table as below, </p>
  
  <pre><code>Product Promotion exists (Y/N)  Week
      A   Y   1
      B   Y   1
      C   Y   1
      A   Y   2
      B   Y   2
      C   N   2
      A   Y   3
      B   Y   3
      C   Y   3
      A   Y   4
      B   Y   4
      C   N   4
  </code></pre>
  
  <p>I want to see an Promition exists combination Output on total table. Something like</p>
  
  <pre><code>A, B - 4
  B,C  - 2
  A,C - 2
  </code></pre>
  
  <p>Since this is Just for 3 products looks simple.. I am looking at some thousands of records, and looking for same combinations where total count of occurrence is greater than some number. If taking the above example, if that count is 4.. then my output should be</p>
  
  <pre><code>A,B - 4
  </code></pre>