涉及多表Oracle、PL/SQL的触发器

Question

我是 SQL 新手，我正在尝试找出触发器。我需要写一个涉及3个表的触发器，不用担心它只被其中一个表触发...

CREATE TABLE CUSTOMERS 
(CUSTID CHAR(8) constraint customers_pk primary key, 
CREDITSCORE NUMBER(5,2)

CREATE TABLE LOANDETAILS 
(LOANNO VARCHAR2(11) primary key, 
CUSTID CHAR(8),  
LOANSTATUSCODE NUMBER(3,0), 
RATE NUMBER(5,2), 

CREATE TABLE SCORECONVERSIONCHART 
(SCOREBAND VARCHAR2(1) constraint scorecc_pk primary key, 
MINSCORE NUMBER(3,0), 
MAXSCORE NUMBER(3,0), 
BASERATEADJUSTMENT NUMBER(4,2)
);

因此，当客户表中的信用评分（creditscore）更新时，我想查看贷款详细信息表中的贷款类型（LOANTYPE）。如果贷款类型是 1 或 2，我想更新贷款详细信息表中的贷款利率。通过查看分数转换表中的自定义信用评分（客户表中的信用评分）来更新贷款利率 - 如果它落在转换表中给定的最小和最大分数之间，则将适当的 baserateadjustment 添加到基础3%。

我不清楚如何让所有这些表在触发器中进行交互，

如果有人可以用通俗易懂的语言帮助我或向我指出一个很好的资源，我将不胜感激。

Answer 1

以下示例可能会为您提供一个起点。
此触发器将有条件地更新LOANDETAILS，如果贷款类型为可调整类型，则仅在更新信用评分时通过SCORECONVERSIONCHART 中的转换。

首先，添加一些测试数据：

INSERT INTO CUSTOMERS VALUES ('00000000','Frodo','Baggins',null,null,null,'frodo@hobbiton.com',123,750);
INSERT INTO CUSTOMERS VALUES ('00000001','Chewbacca','?',null,null,null,'chewie@hoth.com',456,775);


INSERT INTO LOANDETAILS VALUES ('A',NULL,'00000000','1',NULL,NULL,7.2,NULL,NULL);
INSERT INTO LOANDETAILS VALUES ('B',NULL,'00000001','3',NULL,NULL,4.2,NULL,NULL);

INSERT INTO SCORECONVERSIONCHART VALUES ('X',500,599,22);
INSERT INTO SCORECONVERSIONCHART VALUES ('Y',600,699,3);
INSERT INTO SCORECONVERSIONCHART VALUES ('Z',700,799,1);
COMMIT;

然后创建TRIGGER 编辑 最初的例子假设每个客户只有一笔贷款。已更新以处理每位客户的多笔贷款。

CREATE OR REPLACE TRIGGER Q2
AFTER UPDATE OF CREDITSCORE
  ON CUSTOMERS
FOR EACH ROW
  DECLARE
    V_LOAN_TYPE NUMBER;
  BEGIN
      UPDATE LOANDETAILS
      SET RATE = (SELECT SCORECONVERSIONCHART.BASERATEADJUSTMENT + 3
                  FROM SCORECONVERSIONCHART
                  WHERE :NEW.CREDITSCORE BETWEEN SCORECONVERSIONCHART.MINSCORE
                  AND SCORECONVERSIONCHART.MAXSCORE)
      WHERE LOANDETAILS.CUSTID = :NEW.CUSTID
      AND LOANDETAILS.LOANTYPE IN ('1','2');
END;
/

然后，测试它：

SELECT CUSTID, LOANTYPE, RATE FROM LOANDETAILS;
CUSTID    LOANTYPE  RATE  
00000000  1         7.2   
00000001  3         4.2   

然后，更新一个非信用评分属性：

UPDATE CUSTOMERS SET STATE = 'WI';
SELECT CUSTID, LOANTYPE, RATE FROM LOANDETAILS;
CUSTID    LOANTYPE  RATE  
00000000  1         7.2   
00000001  3         4.2   

然后更新信用评分。 Frodo 的贷款更改（他的贷款类型符合条件）为 3% + scoreconversionchart 调整 3%，但 Chewie 的贷款完全没有变化。

UPDATE CUSTOMERS SET CREDITSCORE = 600;
SELECT CUSTID, LOANTYPE, RATE FROM LOANDETAILS;
CUSTID    LOANTYPE  RATE  
00000000  1         6     
00000001  3         4.2   

如果贷款类型是数字，我建议将它们记录为数字。

Answer 2

您可以执行以下操作。

    CREATE OR REPLACE TRIGGER trig
        AFTER UPDATE OF CREDITSCORE 
        ON CUSTOMERS
        FOR EACH ROW
        DECLARE
        temp_RATE LOANDETAILS.RATE%type
        temp_adj  SCORECONVERSIONCHART.BASERATEADJUSTMENT%type;
        BEGIN
        UPDATE LOANDETAILS
        SET RATE = RATE + 0.03* ( select s.BASERATEADJUSTMENT from customer c join loandetails l on c.custid=l.custid cross join SCORECONVERSIONCHART s where new.crediscore between s.minscore and s.maxscore and l.LOANTYPE in (1,2) and c.custid=new.custid)
WHERE CUSTID= ( select c.custid from customer c join loandetails l on c.custid=l.custid cross join SCORECONVERSIONCHART s where new.crediscore between s.minscore and s.maxscore and l.LOANTYPE in (1,2) and c.custid=new.custid)

        END IF;
        END;
        /

现在使用上面的子查询，您将获得符合条件的客户的基本比率。您可以根据您的要求更改该费率。