title: excel - wrap cell in quotes unless value is NULL
body: <p>I have a table in excel that I'm eventually going to read into a sql database. I have  \"@\" as a custom code to wrap the text with quotes. However, I also tried to replace all the blank values with NULL, but those also get quotes wrapped around them.</p>
  
  <p>Is there a custom code I can use that'll wrap every string except NULL in text? </p>