title: To_char function in databricks
body: <p>I am using sql as language for my notebook in databricks.
  Want to get the day of week from the date given.
  For doing this i used to_char(date,'fmday').  Getting error as function is not registered as temporary or permanant in databricks. Is there a way to get the name of day by other means.
  Date is in format yyyymmdd</p>