使用编译错误创建触发器

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:

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,所以我不能保证我找到了你所有的错误.但是,我可以说以下内容:

1. 我不相信你能做到SELECT (....).CLIENTNO.试试吧SELECT x.CLIENTNO FROM (....) x.
2. 你的最外层SELECT没有FROM条款.尝试添加FROM DUAL,因为这个最外层SELECT不是从任何表中选择.
3. PL/SQL赋值运算符:=不是=.要分配:NEW.AMOUNT,你需要写:NEW.AMOUNT := (:NEW.AMOUNT * 0.1);.
4. 将金额乘以0.1可为客户提供90%的折扣,而不是10%的折扣.