触发器和计数（*）不起作用

Question

我写了触发器来检查客户是否有任何暂停的帐户。如果是，他将无法创建新帐户，但是当我尝试插入时，插入仍然会通过。有人可以帮助我吗？

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; 

对不起，我试图更改为0，因为它永远是“空”，但它仍然没有工作

Answer 1

，您的触发并不做任何事情来阻止INSERT - 只返回过早退出触发器主体。

如果你想防止INSERT，你应该提出一个例外，而不是：

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

Answer 2

的问题是你的其他条件！

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

试着将下面的代码

ELSIF (varIsProblemAccount = null) THEN 

到

ELSIF (varIsProblemAccount = 0) THEN