title: How to prompt an error msg in Excel, if a cell is blank using excel formula
body: <p>I have an excel as shown in the screenshot below screenshot</p>
  <p><a href="https://i.stack.imgur.com/8lQF9.png" rel="nofollow noreferrer">enter image description here</a></p>
  <p>now as per our formula, when the if condition is false, then i want it to show out as an excel error msg, to notify user that they have to enter a value for column2, while saving or when column1 has data.</p>
  <p>I tried adding as Data Validation, not sure how to write the false condition.</p>
  <p><a href="https://i.stack.imgur.com/Qs1Em.png" rel="nofollow noreferrer">enter image description here</a></p>