Sql 插入之前的Oracle触发器找不到数据

如果账单已经支付，我试图触发一个触发器，阻止您在“Bill\u Item”表中插入新的账单项。账单表中有一个Paid_YN和一个Posted_YN列。因此，根据您将要添加到的账单，如果该账单已经支付或过账，它将拒绝该账单。我的更新和删除部分在此代码范围内工作，但不是“插入”部分。请帮忙！很抱歉没有缩进，无法正确复制代码。 请告诉我哪里出了问题！这是我的逻辑吗？我已经尝试过在这里搜索错误信息，但仍然无法找到它

表格：：

CREATE TABLE Bill (
Bill_Number NUMBER (6,0)
CONSTRAINT Bill_pk PRIMARY KEY
CONSTRAINT Bill_Number_NN NOT NULL,
Bill_Date DATE DEFAULT SYSDATE
CONSTRAINT Bill_Date_NN NOT NULL,
Waiter_Number NUMBER (5,0)
CONSTRAINT Bill_Waiter_Number_FK REFERENCES Waiter (Waiter_Number)
CONSTRAINT Bill_Waiter_Number_NN NOT NULL,
Table_Number NUMBER (2,0)
CONSTRAINT Bill_Table_Number_NN NOT NULL,
Customer_Count NUMBER (2,0) DEFAULT 1
CONSTRAINT Bill_Customer_Count_CK CHECK (Customer_Count > 0)
CONSTRAINT Bill_Customer_Count_NL NULL,
Paid_YN CHAR (1) DEFAULT 'N'
CONSTRAINT Bill_Paid_YN_CK CHECK ((Paid_YN = 'Y') OR (Paid_YN = 'N'))
CONSTRAINT Bill_Paid_YN_NN NOT NULL,
Posted_YN CHAR (1) DEFAULT 'N'
CONSTRAINT Bill_Posted_YN_CK CHECK ((Posted_YN = 'Y') OR (Posted_YN = 'N'))
CONSTRAINT Bill_Posted_YN_NN NOT NULL,
Bill_GST NUMBER (6,2) DEFAULT 0
CONSTRAINT Bill_GST_CK CHECK (Bill_GST >= 0)
CONSTRAINT Bill_GST_NN NOT NULL,
Bill_Total NUMBER (8,2) DEFAULT 0
CONSTRAINT Bill_Total_CK CHECK (Bill_Total >= 0)
CONSTRAINT Bill_Total_NN NOT NULL
);

CREATE TABLE Bill_Item (
Bill_Number NUMBER (6,0)
CONSTRAINT BItem_Bill_Number_FK REFERENCES Bill (Bill_Number)
CONSTRAINT BItem_Bill_Number_NN NOT NULL,
Menu_Item_Number NUMBER (5,0)
CONSTRAINT BItem_Menu_Item_Number_FK REFERENCES Menu_Item (Menu_Item_Number)
CONSTRAINT BItem_Menu_Item_Number_NN NOT NULL,
Discount NUMBER (5,2) DEFAULT 0
CONSTRAINT BItem_Discount_CK CHECK ((Discount >= 0 ) AND (Discount <= 100))
CONSTRAINT BItem_Discount_NL NULL,
Quantity_Sold NUMBER (3,0) DEFAULT 1
CONSTRAINT BItem_Quantity_Sold_CK CHECK (Quantity_Sold > 0)
CONSTRAINT BItem_Quantity_Sold_NN NOT NULL,
Selling_Price NUMBER (6,2) DEFAULT 0
CONSTRAINT BItem_Selling_Price_CK CHECK (Selling_Price >= 0)
CONSTRAINT BItem_Selling_Price_NN NOT NULL,
CONSTRAINT Bill_Item_PK PRIMARY KEY (Bill_Number, Menu_Item_Number)
);

此插入返回：

Insert Into Bill_Item
    (Bill_Number, Menu_Item_Number, Discount, Quantity_Sold, Selling_Price)
Values
  (4945, 2, 0, 1, 1.03);


Error starting at line : 234 in command -
Insert Into Bill_Item
    (Bill_Number, Menu_Item_Number, Discount, Quantity_Sold, Selling_Price)
Values
   (4945, 2, 0, 1, 1.03)
Error report -
SQL Error: ORA-01403: no data found
ORA-06512: at "ORCL1_05.TR_Q5", line 24
ORA-04088: error during execution of trigger 'ORCL1_05.TR_Q5'
01403. 00000 -  "no data found"
*Cause:    No data was found from the objects.
*Action:   There was no data from the objects which may be due to end of 
fetch.

这是你的灯笼裤：

  ELSIF INSERTING THEN
    SELECT Paid_YN, Posted_YN
    INTO v_paid_YN, v_Posted_Yn
    FROM Bill
    WHERE Bill_Number = :OLD.Bill_Number;

在插入过程中，

：old

命名空间为空。这是完全合乎逻辑的：我们正在插入一条记录，旧记录还能是什么

因此，解决方案非常简单

  ELSIF INSERTING THEN
    SELECT Paid_YN, Posted_YN
    INTO v_paid_YN, v_Posted_Yn
    FROM Bill
    WHERE Bill_Number = :NEW.Bill_Number;

：旧的

在更新和删除时有效，这就是这些分支工作的原因。（通常在更新时测试当前值：新值，除非检查值是否已更改。）

这是您的灯笼裤：

  ELSIF INSERTING THEN
    SELECT Paid_YN, Posted_YN
    INTO v_paid_YN, v_Posted_Yn
    FROM Bill
    WHERE Bill_Number = :OLD.Bill_Number;

在插入过程中，

：old

命名空间为空。这是完全合乎逻辑的：我们正在插入一条记录，旧记录还能是什么

因此，解决方案非常简单

  ELSIF INSERTING THEN
    SELECT Paid_YN, Posted_YN
    INTO v_paid_YN, v_Posted_Yn
    FROM Bill
    WHERE Bill_Number = :NEW.Bill_Number;

---

：旧的

在更新和删除时有效，这就是这些分支工作的原因。（除了检查值是否已更改外，更新时通常会测试当前的-

：new

-值。）

插入时是否应使用：new.Bill\u编号？另外，如果这是一条全新的记录，您必须检查未发现数据时的异常：

未发现数据时的异常

插入时是否应该使用：new.Bill\u编号？此外，如果这是一条全新的记录，您必须检查未发现数据时的异常：

未发现数据时的异常

非常感谢！这样解释就有意义了！非常感谢你！这样解释就有意义了！