plsql - 为什么我会收到 PL/SQL 触发器错误 PLS-00103？

Question

如果表的字段已经具有某些值，我已经编写了一个不更新表字段的触发器：

CREATE TRIGGER DO_NOT_UPDATE BEFORE UPDATE ON CONCERNED_TABLE
FOR EACH ROW
BEGIN
   IF :OLD.CONCERNED_FIELD IS NOT NULL 
   THEN
      RAISE_APPLICATION_ERROR(-20182,'Concerned dataitem already exists!');
   END IF;
END;

我在编译时收到此错误：

LINE/COL ERROR
-------- -----------------------------------------------------------------
5/3      PLS-00103: Encountered the symbol "end-of-file" when expecting
         one of the following:
         ; <an identifier> <a double-quoted delimited-identifier>
         The symbol ";" was substituted for "end-of-file" to continue.

看起来是什么问题？我完全忽略了一些东西。