title: Count unique values using countifs?
body: <p>I'm trying to create a gift table. Here is some sample data:</p>
  
  <pre><code>Gift    Donor ID
  $1      100
  $1      151
  $2      100
  $2      186
  $2      124
  $4      124
  $4      178
  $4      162
  $5      100
  $5      158
  </code></pre>
  
  <p>In column A I've written a formula that counts the number of gifts greater then $1 and less than or equal to $4. There are 6.</p>
  
  <pre><code> =COUNTIFS(A2:A11,"&gt;1",A2:A11,"&lt;=4")
  </code></pre>
  
  <p>Now what I need to do is count the number of unique donors from column B who meet the criteria from column A. In this case there are 5. What would that formula look like?</p>