title: SSIS add new column C based on if value in column A exists in column B
body: <p>I have a dataset, getting from a web service as following,</p>
  
  <pre><code>ColumnA ....  ColumnB...
  userA         NULL
  userB         userA
  userC         NULL
  userD         userC
  </code></pre>
  
  <p>What I want is </p>
  
  <pre><code>ColumnA ....  ColumnB...   ColumnC (if columnA's value exists in column B, position doesn't matter)
  userA         NULL         YES 
  userB         userA        NO
  userC         NULL         YES
  userD         userC        NO
  </code></pre>
  
  <p>Being new to SSIS, I am not sure if it's even possible, google is not helping much, can i do this without getting create a task using C# ?</p>
  
  <p><strong>Edit</strong></p>
  
  <p>Explaining further, </p>
  
  <pre><code>ColumnC = Value of ColumnA exists in ***ANY*** of ColumnB row. 
  </code></pre>
  
  <p>E.g. userA has value NULL in columnB but it's used in one or more rows of ColumnB hence ColumnC value is YES.</p>
  
  <p>So in terms of logic it will be,</p>
  
  <ul>
  <li>Get distinct values from ColumnB and put them in let say a listA</li>
  <li>Foreach value in ColumnA if value exists in listA then columnC will be YES otherwise NO</li>
  </ul>