title: Google sheets date in dd-mm-yy format to month in mmm-yyyy format in another column
body: <p>How do I convert a date in dd-mm-yy format in Google sheets to just month in mmm-yyyy format in another column so that dates within the same month have the same value in month format. 
  Currently it's showing different dates as multiple values in my pivot table and I want to show totals for the month or it shows the order wrong because the month is a text value.
  <a href="https://i.stack.imgur.com/MA1Y3.jpg" rel="nofollow noreferrer">Alpha sort not chronological sort</a></p>