title: How to convert a column in dataframe from date format "MDDYY" to date format "YYYYMMDD"
body: <p>This is the first dataset's date format, it is in &quot;YYYYMMDD&quot; format</p>
  <p><img src="https://i.stack.imgur.com/ctMtd.png" alt="This is the first dataset's date format, it is in &quot;YYYYMMDD&quot; format" /></p>
  <p>This is the second dataset's date format, it is in &quot;MDDYY&quot; format
  <img src="https://i.stack.imgur.com/U9UK1.png" alt="This is the second dataset's date format, it is in &quot;MDDYY&quot; format" /></p>
  <p>How could I convert the dates reported in the second dataset to the format used in the first (YYYYMMDD)
  I got stuck on this question and my code doesn't make sense.
  Please give me some example for this, the date needs to stay in &quot;as.data.frame</p>