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[英]How to create trigger in oracle with IF-else statement, and output should be a description
[英]Trigger if-else statement error not being raised
我已經創建了一個程序和一個觸發器,我打算支付票價,輸入的票價金額必須大於或等於支付表中的確切金額
從表中我的意思是,用戶需要輸入足夠的數量才能繼續存儲過程,如果輸入的數量低於該數量,則會引發觸發器錯誤!
CREATE OR REPLACE PROCEDURE PRC_PAY_TRIP
(CUST_ID IN NUMBER,PAYMENT_ID IN NUMBER,PAYMENT_TYPE IN VARCHAR2,AMT_PAY IN NUMBER)
AS
v_paymentstatus VARCHAR2(15) := 'Paid';
v_temppaymentid NUMBER(4) := PAYMENT_ID;
v_truenumber NUMBER(10);
no_null_on_custID EXCEPTION;
no_null_on_payID EXCEPTION;
invalid_paymentid EXCEPTION;
invalid_paymenttype EXCEPTION;
invalid_paymentamt EXCEPTION;
BEGIN
v_truenumber := v_temppaymentid-1000;
IF CUST_ID < 0
THEN
RAISE no_null_on_custID;
END IF;
IF PAYMENT_ID < 0
THEN
RAISE no_null_on_payID;
END IF;
IF CUST_ID ^= v_truenumber THEN
RAISE invalid_paymentid;
END IF;
IF PAYMENT_TYPE ^= 'Cash' AND PAYMENT_TYPE ^= 'E-Wallet' THEN
RAISE invalid_paymenttype;
END IF;
IF AMT_PAY < 0 THEN
RAISE invalid_paymentamt;
END IF;
UPDATE Payment
SET paymenttype = PAYMENT_TYPE,paymentdate = TO_CHAR(sysdate,'DD/MON/YYYY'), paymentstatus = v_paymentstatus
where paymentid = PAYMENT_ID;
EXCEPTION
WHEN no_null_on_custID then
DBMS_OUTPUT.PUT_LINE('Invalid Customer ID');
WHEN no_null_on_payID then
DBMS_OUTPUT.PUT_LINE('Invalid Payment ID');
WHEN invalid_paymenttype then
DBMS_OUTPUT.PUT_LINE('You can either choose Cash or E-Wallet only!');
WHEN invalid_paymentid then
DBMS_OUTPUT.PUT_LINE('Payment id is not yours, just add 1000 from your Customer ID and that will be your Payment ID');
WHEN invalid_paymentamt then
DBMS_OUTPUT.PUT_LINE('Amount pay cannot be negative value!');
END;
/
CREATE OR REPLACE trigger trg_payment_validation
before update on payment
for each row
BEGIN
if :NEW.paymentamount < :OLD.paymentamount then >>> this error could not be raised even after
the amount entered is lower than the
actual amount
RAISE_APPLICATION_ERROR(
-20950,
'Insufficient amount entered, pls pay the exact amount'
);
elsif :OLD.paymentstatus = 'Paid' then
RAISE_APPLICATION_ERROR(
-20950,
'You cannot pay the fares as you already paid before this, have a nice day'
);
end if;
END;
/
當您手動更新表時,觸發器會按預期工作。
當從過程中調用時,觸發器不會報告無效金額,並顯示已支付的全部金額,即使它沒有——支付金額沒有改變,但其他列是。
那是因為你程序的更新語句是:
UPDATE Payment
SET paymenttype = PAYMENT_TYPE,
paymentdate = TO_CHAR(sysdate,'DD/MON/YYYY'),
paymentstatus = v_paymentstatus
where paymentid = PAYMENT_ID;
您沒有告訴它更新金額,因此觸發器沒有修改后的:new
值 - 舊值和新值相同。 您需要在更新中包括該列:
UPDATE Payment
SET paymenttype = PAYMENT_TYPE,
paymentdate = TO_CHAR(sysdate,'DD/MON/YYYY'),
paymentamount = amt_pay,
paymentstatus = v_paymentstatus
where paymentid = PAYMENT_ID;
TO_CHAR(sysdate,'DD/MON/YYYY')
看起來很奇怪 - 表列應該是日期而不是字符串,因此您不應該將該值轉換為字符串; 如果該列是日期,那么您將依靠客戶端的 NLS 設置將其轉換回來。 如果您試圖忽略當前時間,那么您可以改為執行TRUNC(sysdate)
。
您也不應該依賴過程主體中的dbms_output
- 您無法控制調用它的人是否啟用了 output,因此他們可能永遠看不到問題。 當您在觸發器中引發異常時,您可以在其他錯誤的過程中執行相同的操作。
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