涉及多个表的触发器Oracle，PL/SQL

Question

我是SQL新手，我试图找出触发器。我需要编写一个涉及3个表的触发器，不用担心它仅由表中的一个触发...

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) 
); 

所以，当从客户表中的信用评分（CreditScore等）被更新，我想要查看贷款细节表中的贷款类型（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。通过在分数转换图表中查看自定义信用评分下降的位置（客户表格中的信用分数）来更新贷款利率 - 如果它落入转换图表中给定的最小和最大分数之间，则将适当的基准调整量添加到基准率3％。

我不清楚如何获得这些表格来在触发交互，

如果有人可以帮助我用通俗易懂的语言或指向我一个很好的资源，我将不胜感激。

Answer 1

以下示例可能会为您提供一个开始位置。
如果贷款类型属于可调整类型，则此触发器将有条件地更新LOANDETAILS，仅在信用分数更新后，通过SCORECONVERSIONCHART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 编辑假定原来的例子有每个客户只有一个贷款。更新后处理每个客户的多笔贷款。

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，更新非信用得分属性：

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

然后更新信用分数。佛罗多的贷款变化（他的贷款类型是合格的）至3％+分数转换图调整为3％，但Chewie's根本不动。

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

你可以做下面的事情。

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，通过上述子查询，您将得到符合条件的客户的基础。您可以根据您的要求更改该费率。