Built-in functions that you cannot overload

You cannot overload aggregate functions, status functions, and certain other built-in functions.

The following functions cannot be overloaded:

  • add_months()
  • Aggregate functions. Each aggregate function uses built-in functions to generate the aggregate result, which you can overload. For a list of the aggregate functions and their related operator functions, see Overload operators for built-in aggregates.
  • cardinality()
  • concat()
  • current
  • date()
  • datetime()
  • day()
  • dbinfo()
  • dbservername
  • descr()
  • family()
  • format_units()
  • last_day()
  • ltrim()
  • mdy()
  • month()
  • months_between()
  • next_day()
  • round()
  • rtrim()
  • sitename
  • sysdate()
  • today
  • to_char()
  • to_number()
  • trim()
  • trunc()
  • user
  • volume()
  • weekday()
  • year()
Tip: Technically, CURRENT, DBSERVERNAME, SITENAME, TODAY, and USER, are not built-in functions, but built-in macros. You can register overloaded routines by those names, but you cannot use them in SQL statements.