CREATE [ OR REPLACE ] FUNCTION [ schema. ]function
  [ (argument [ IN | OUT | IN OUT ]
     [ NOCOPY ] datatype
       [, argument [ IN | OUT | IN OUT ]
          [ NOCOPY ] datatype
       ]...
    )
  ]
  RETURN datatype
  [ { invoker_rights_clause
    | DETERMINISTIC
    | parallel_enable_clause
    }
      [ invoker_rights_clause
      | DETERMINISTIC
      | parallel_enable_clause
      ]...
  ]
  { { AGGREGATE | PIPELINED }
    USING [ schema. ]implementation_type
  | [ PIPELINED ]
    { IS | AS }
    { pl/sql_function_body | call_spec }
  } ;