Question

我写了这个触发器，在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，我会收到以下消息：

Warning: Trigger created with compilation errors.

有人可以告诉我我做错了吗？

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;
/

Answer 1

我没有你的桌子，所以我无法保证我找到了你所有的错误。但是，我可以说以下内容：

我认为你不能做SELECT (....).CLIENTNO。请改为SELECT x.CLIENTNO FROM (....) x。
您最外面的SELECT没有FROM条款。请尝试添加FROM DUAL，因为此最外层SELECT未从任何表中进行选择。
PL / SQL赋值运算符为:=，而不是=。要分配到:NEW.AMOUNT，您需要撰写:NEW.AMOUNT := (:NEW.AMOUNT * 0.1);。
将金额乘以0.1可为客户提供90％的折扣，而不是10％的折扣。

Answer 2

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;

Answer 3

除了其他人识别的语法错误之外，很可能您正在获得一个变异触发器，因为您无法从正在插入的表中进行选择。

如果您可以更改数据模型，则可能需要在另一个表中标识顶级客户端，而不是在插入该表时尝试选择金额购买表的总和。

使用编译错误创建触发器

3 个答案: