觸發器和計數（*）不起作用

Question

我寫了觸發器來檢查客戶是否有任何暫停的帳戶。如果是，他將無法創建新帳戶，但是當我嘗試插入時，插入仍然會通過。有人可以幫助我嗎？

CREATE OR REPLACE TRIGGER SuspendedAccount 
BEFORE INSERT ON ACCOUNT 

FOR EACH ROW 

DECLARE 

varIsProblemAccount Int; 

BEGIN 

SELECT COUNT(*) INTO varIsProblemAccount 
FROM ACCOUNT 
WHERE CUSTID = :new.custID 
    AND ACCSTATUS = 'Suspended'; 

IF (varIsProblemAccount >= 1) THEN  
     DBMS_OUTPUT.PUT_LINE('*************************************************'); 
     DBMS_OUTPUT.PUT_LINE(''); 
     DBMS_OUTPUT.PUT_LINE(' Transaction canceled. '); 
     DBMS_OUTPUT.PUT_LINE(''); 
     DBMS_OUTPUT.PUT_LINE(' Refer customer to the manager immediately. '); 
     DBMS_OUTPUT.PUT_LINE(''); 
     DBMS_OUTPUT.PUT_LINE('**************************************************'); 
     RETURN; 
    END; 

ELSIF (varIsProblemAccount = 0) THEN 

    BEGIN 
     DBMS_OUTPUT.PUT_LINE('*************************************************'); 
     DBMS_OUTPUT.PUT_LINE(''); 
     DBMS_OUTPUT.PUT_LINE(' Transaction completed. '); 
     DBMS_OUTPUT.PUT_LINE(''); 
     DBMS_OUTPUT.PUT_LINE(' Thank the customer for their business. '); 
     DBMS_OUTPUT.PUT_LINE(''); 
     DBMS_OUTPUT.PUT_LINE('**************************************************'); 
    END; 
END IF; 
END; 

對不起，我試圖更改爲0，因爲它永遠是「空」，但它仍然沒有工作

Answer 1

，您的觸發並不做任何事情來阻止INSERT - 只返回過早退出觸發器主體。

如果你想防止INSERT，你應該提出一個例外，而不是：

IF (varIsProblemAccount >= 1) THEN  
    raise_application_error(-20001, 'Existing account found'); 
END; 

Answer 2

的問題是你的其他條件！

CREATE OR REPLACE TRIGGER SuspendedAccount 
BEFORE INSERT ON ACCOUNT 

FOR EACH ROW 

DECLARE 

varIsProblemAccount Int; 

BEGIN 

SELECT COUNT(*) INTO varIsProblemAccount 
FROM ACCOUNT 
WHERE CUSTID = :new.custID 
    AND ACCSTATUS = 'Suspended'; 

IF (varIsProblemAccount >= 1) THEN  
     DBMS_OUTPUT.PUT_LINE('*************************************************'); 
     DBMS_OUTPUT.PUT_LINE(''); 
     DBMS_OUTPUT.PUT_LINE(' Transaction canceled. '); 
     DBMS_OUTPUT.PUT_LINE(''); 
     DBMS_OUTPUT.PUT_LINE(' Refer customer to the manager immediately. '); 
     DBMS_OUTPUT.PUT_LINE(''); 
     DBMS_OUTPUT.PUT_LINE('**************************************************'); 
     RETURN; 
    END; 

-- count() never returns NULL 
ELSIF (varIsProblemAccount = 0) THEN 

    BEGIN 
     DBMS_OUTPUT.PUT_LINE('*************************************************'); 
     DBMS_OUTPUT.PUT_LINE(''); 
     DBMS_OUTPUT.PUT_LINE(' Transaction completed. '); 
     DBMS_OUTPUT.PUT_LINE(''); 
     DBMS_OUTPUT.PUT_LINE(' Thank the customer for their business. '); 
     DBMS_OUTPUT.PUT_LINE(''); 
     DBMS_OUTPUT.PUT_LINE('**************************************************'); 
    END; 
END IF; 
END; 

Answer 3

試着將下面的代碼

ELSIF (varIsProblemAccount = null) THEN 

到

ELSIF (varIsProblemAccount = 0) THEN