title: Convert pyspark string to date format
body: <p>I have a date pyspark dataframe with a string column in the format of <code>MM-dd-yyyy</code> and I am attempting to convert this into a date column.</p>
  <p>I tried:</p>
  <pre><code>df.select(to_date(df.STRING_COLUMN).alias('new_date')).show()
  </code></pre>
  <p>And I get a string of nulls. Can anyone help?</p>