使用编译错误创建的触发器

Question

我编写了这个触发器，以便在进行新购买时将数据库中的顶级客户折扣 10%：

 CREATE or REPLACE TRIGGER CLIENT_DISCOUNT
  BEFORE INSERT
  ON PURCHASE
  FOR EACH ROW
DECLARE
  CLIENTNO  NUMBER(5);
BEGIN
  SELECT (SELECT CLIENT.CLIENTNO, CLIENT.CNAME, TOTALS.TOTAL FROM CLIENT,
    (SELECT CLIENTNO, SUM(AMOUNT) AS TOTAL FROM PURCHASE GROUP BY CLIENTNO) TOTALS WHERE CLIENT.CLIENTNO = TOTALS.CLIENTNO  AND ROWNUM <= 1 ORDER BY TOTALS.TOTAL DESC).CLIENTNO INTO CLIENTNO;
  IF :NEW.CLIENTNO = CLIENTNO THEN
    :NEW.AMOUNT = (:NEW.AMOUNT * 0.1);
  END IF;
END;

但是，当我执行此语句时，我收到此消息：

 Warning: Trigger created with compilation errors.

有人可以告诉我我做错了什么吗？

谢谢，亚历克斯。

更新 - 错误：

 Errors for TRIGGER CLIENT_DISCOUNT:

LINE/COL
--------------------------------------------------------------------------------
ERROR
--------------------------------------------------------------------------------
4/3
PL/SQL: SQL Statement ignored

5/141
PL/SQL: ORA-00907: missing right parenthesis

7/17
PLS-00103: Encountered the symbol "=" when expecting one of the following:

LINE/COL
--------------------------------------------------------------------------------
ERROR
--------------------------------------------------------------------------------
   := . ( @ % ; indicator

8/3
PLS-00103: Encountered the symbol "END"

解决方案：

 CREATE or REPLACE TRIGGER CLIENT_DISCOUNT
    BEFORE INSERT
    ON PURCHASE
    FOR EACH ROW
DECLARE
    vCLIENTNO  NUMBER(5);
BEGIN
    SELECT TOPCLIENT.CLIENTNO INTO vCLIENTNO FROM (SELECT CLIENT.CLIENTNO, CLIENT.CNAME, TOTALS.TOTAL FROM CLIENT, (SELECT CLIENTNO, SUM(AMOUNT) AS TOTAL FROM PURCHASE GROUP BY CLIENTNO) TOTALS WHERE CLIENT.CLIENTNO = TOTALS.CLIENTNO  AND ROWNUM <= 1 ORDER BY TOTALS.TOTAL DESC) TOPCLIENT;
    IF :NEW.CLIENTNO = vCLIENTNO THEN
        :NEW.AMOUNT := (:NEW.AMOUNT * 0.9);
    END IF;
END;
/

原文由 Alex Hope O‘Connor 发布，翻译遵循 CC BY-SA 4.0 许可协议

Answer 1

我手头没有你的桌子，所以我不能保证我找到了你所有的错误。但是，我可以说以下几点：

1. 我不相信你能做到 SELECT (....).CLIENTNO 。尝试 SELECT x.CLIENTNO FROM (....) x 代替。
2. 您最外面的 SELECT 没有 FROM 子句。尝试添加 FROM DUAL ，因为最外面的 SELECT 没有从任何表中选择。
3. PL/SQL 赋值运算符是 := ，而不是 = 。要分配给 :NEW.AMOUNT ，您需要编写 :NEW.AMOUNT := (:NEW.AMOUNT * 0.1); 。
4. 将金额乘以 0.1 会给客户 90% 的折扣，而不是 10% 的折扣。

原文由 Luke Woodward 发布，翻译遵循 CC BY-SA 3.0 许可协议

Answer 2

尝试

CREATE or REPLACE TRIGGER CLIENT_DISCOUNT
  BEFORE INSERT
  ON PURCHASE
  FOR EACH ROW
DECLARE
  vCLIENTNO  NUMBER(5);
BEGIN
  SELECT Z.CLIENTNO INTO vCLIENTNO FROM (SELECT CLIENT.CLIENTNO, CLIENT.CNAME, TOTALS.TOTAL FROM CLIENT,
    (SELECT CLIENTNO, SUM(AMOUNT) AS TOTAL FROM PURCHASE GROUP BY CLIENTNO) TOTALS WHERE CLIENT.CLIENTNO = TOTALS.CLIENTNO  AND ROWNUM <= 1 ORDER BY TOTALS.TOTAL DESC) Z;
  IF :NEW.CLIENTNO = vCLIENTNO THEN
    :NEW.AMOUNT := (:NEW.AMOUNT * 1.091);
  END IF;
END;

原文由 Yahia 发布，翻译遵循 CC BY-SA 3.0 许可协议