title: How to derive one column from two columns based on logical expressions in SSIS?
body: <p>I would like to derive one additional column from two columns based on some logical statements:</p>
  
  <pre><code>table
  id col1 col additionalcol
  1    a        a
  2    b    c   c
  3    d    e   e
  4         f   f
  5    g    me  g
  6    i    me  i
  7    j    l   l
  8    k    m   m
  9    n    me  n
  10   o    p   p
  </code></pre>
  
  <p>I would like to derive an <code>additionalcol</code> based on the statement:</p>
  
  <pre><code>        `if 
              col is empty  or me then
                  take col1
          else    
              take col
  </code></pre>