title: How to check if value exists in other sheet, then output value from another cell in the row
body: <p>I am completely stumped here and don't know the proper spreadsheet terminology.</p>
  
  <p>So I have one sheet which has the following three columns</p>
  
  <ul>
  <li>Comment ID</li>
  <li>Comment Post ID</li>
  <li>Comment</li>
  </ul>
  
  <p>Now the post ID refers to the ID of the post the comment was created on.</p>
  
  <p>I have a second sheet (in the same workbook) that has the following columns:</p>
  
  <ul>
  <li>Post ID</li>
  <li>Post Title</li>
  </ul>
  
  <p>How can I run a formula that makes Excel replace the values in 'Comment Post ID' with the correlating titles?</p>
  
  <p>Thanks!</p>