dayname

Returns a character string containing the data source-specific name of the day (for example, Sunday through Saturday or Sun. through Sat. for a data source that uses English, or Sonntag through Samstag for a data source that uses German) for the day portion of "date_expression". "Date_expression" can be a date value or a string representation of a date.

dayname ( date_expression )

dayname ( '1998-01-08' )