涉及多個表的觸發器Oracle，PL/SQL

Question

我是SQL新手，我試圖找出觸發器。我需要編寫一個涉及3個表的觸發器，不用擔心它僅由表中的一個觸發...

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，當從客戶表中的信用評分（CreditScore等）被更新，我想要查看貸款細節表中的貸款類型（LOANTYPE）。如果貸款類型是1或2，我想更新貸款詳細信息表中的貸款利率。通過在分數轉換圖表中查看自定義信用評分下降的位置（客戶表格中的信用分數）來更新貸款利率 - 如果它落入轉換圖表中給定的最小和最大分數之間，則將適當的基準調整量添加到基準率3％。

我不清楚如何獲得這些表格來在觸發交互，

如果有人可以幫助我用通俗易懂的語言或指向我一個很好的資源，我將不勝感激。

Answer 1

以下示例可能會爲您提供一個開始位置。
如果貸款類型屬於可調整類型，則此觸發器將有條件地更新LOANDETAILS，僅在信用分數更新後，通過SCORECONVERSIONCHART轉換。

首先，添加一些測試數據：

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; 

然後創建TRIGGER 編輯假定原來的例子有每個客戶只有一個貸款。更新後處理每個客戶的多筆貸款。

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; 
/

然後，測試它：

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

然後，更新非信用得分屬性：

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

然後更新信用分數。佛羅多的貸款變化（他的貸款類型是合格的）至3％+分數轉換圖調整爲3％，但Chewie's根本不動。

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

如果貸款類型是數字，我建議將它們記錄爲數字。

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; 
     /

現在，通過上述子查詢，您將得到符合條件的客戶的基礎。您可以根據您的要求更改該費率。