我正在尝试使用oracle创建一个函数，它应该可以正常工作，但我不断收到以下错误：

错误（8,1）：PLS-00103：遇到符号“ SET”，这是我的功能：

CREATE OR REPLACE FUNCTION CountViewers(nameofPlay plays.play%TYPE) RETURN NUMBER AS
NUM NUMBER;
  BEGIN
   SELECT SUM(registerd) INTO num1 FROM plays WHERE play=nameofPlay;
   return num;
  END;
SET SERVEROUT ON;
DECLARE
inc integer;
res NUMBER;
invalid_status EXCEPTION;
CURSOR clients2 IS SELECT * FROM plays;
name_of_play  plays.play%ROWTYPE;
play_name plays%TYPE;
BEGIN
inc:=0;
name_of_play := '&Play';
OPEN clients2;
LOOP
       FETCH clients2 INTO play_name;
       IF name_of_play != play_name.play and clients2%rowcount>i THEN 
               inc:=inc+1;
       ELSIF name_of_play = play_name.play THEN
               EXIT WHEN clients2%found;
       ELSE
               RAISE invalid_status;
               --like throw error
       END IF;
EXIT WHEN clients2%notfound;
END LOOP;
res:=CountViewers(name_of_play);
DBMS_OUTPUT.PUT_LINE(name_of_play ||'  | '|| res);
EXCEPTION
   WHEN invalid_status THEN DBMS_OUTPUT.PUT_LINE('The name of play is not found');
END;