创建一个自动更新审计表的审计触发器

Question

我的桌子是

Book

CREATE TABLE Book 
(
    Bk_id CHAR(06)NOT NULL,
    BK_Name VARCHAR(60)NOT NULL,
    Author VARCHAR(30)NOT NULL,
    Price NUMERIC(03)NOT NULL,
    No_of_copies NUMERIC(02)NOT NULL,
    CONSTRAINT Book_PK PRIMARY KEY (Bk_id) 
);

Location

CREATE TABLE Location 
(
    Loc_id CHAR(06)NOT NULL,
    Loc_Name VARCHAR(15)NOT NULL,
    Stock NUMERIC(02)NOT NULL,
    CONSTRAINT Location_PK PRIMARY KEY (Loc_id)
);

Customer

CREATE TABLE Customer 
(
    Cus_id CHAR(06)NOT NULL, 
    Cus_Name VARCHAR(25)NOT NULL,  
    Gender VARCHAR(06)NOT NULL, 
    TP CHAR(12)NOT NULL,
    Address VARCHAR(40)NOT NULL, 
    CONSTRAINT Customer_PK PRIMARY KEY (Cus_id)
);

Copy

CREATE TABLE Copy 
(
Copy_id CHAR(06)NOT NULL,
Bk_id CHAR(06)NOT NULL,
Loc_id CHAR(06)NOT NULL,
Opinion CHAR(02)NOT NULL,
CONSTRAINT pk_Copy PRIMARY KEY (Copy_id),
CONSTRAINT fk_Copy_Bk_id_FK FOREIGN KEY (Bk_id) REFERENCES Book(Bk_id),
CONSTRAINT fk_Copy_Loc_id_FK FOREIGN KEY (Loc_id) REFERENCES Location(Loc_id)
);

Borrow

CREATE TABLE Borrow 
(
    Cus_evo NUMERIC(02)NOT NULL,
    B_Date DATE NOT NULL,
    R_Date DATE NOT NULL,
    Fee NUMERIC(03)NOT NULL,
    Copy_id CHAR(06)NOT NULL,
    Cus_id CHAR(06)NOT NULL,
    CONSTRAINT pk_Borrow PRIMARY KEY (Cus_id,Copy_id),
    CONSTRAINT fk_Borrow_Copy_id_FK FOREIGN KEY (Copy_id) REFERENCES Copy(Copy_id),
    CONSTRAINT fk_Borrow_Cus_id_FK FOREIGN KEY (Cus_id) REFERENCES Customer(Cus_id)
);

Audit_Table

Create table Audit_Table
(
Cus_Name VARCHAR(25)NOT NULL,
BK_Name VARCHAR(60)NOT NULL,
B_Date DATE NOT NULL,
Loc_Name VARCHAR(15)NOT NULL,
Cus_evo NUMERIC(02)NOT NULL
);

如果客户给出零评价Cus_evo=0，他们的借款详情（Cus_Name from CUSTOMER、BK_Name from Book、B_Date from Borrow、Loc_Name来自Location 和Cus_evo 来自Borrow 的副本）必须放在审计表中。

我创建的触发器：

CREATE OR REPLACE TRIGGER "AUDIT_TRIGGER"
BEFORE
INSERT OR UPDATE ON Borrow
FOR EACH ROW
WHEN (new.Cus_evo=0)
BEGIN
INSERT INTO Audit_Table
VALUES (:OLD.Cus_Name, :OLD.BK_Name, :OLD.B_Date, :OLD.Loc_Name, :OLD.Cus_evo);
END;
/

我收到此错误：

错误：TRIGGER AUDIT_TRIGGER 行/列：3/9 PLS-00049：绑定变量“OLD.CUS_NAME”错误 行/列：3/24 PLS-00049：绑定变量“OLD.BK_NAME”错误 行/列：3/51 PLS-00049：错误绑定变量“OLD.LOC_NAME”

Answer 1

1. 在创建触发器时，您不能仅从表 Borrwo 使用其他表中的旧值和新值

2. 您需要在WHEN子句中指定是否要检查新值或旧值

   CREATE OR REPLACE TRIGGER "AUDIT_TRIGGER"
   BEFORE INSERT OR UPDATE ON Borrow --I have removed double quotes
   FOR EACH ROW
   WHEN (new.Cus_evo = 0) -- I have added new. before the name of the column
     BEGIN
        INSERT INTO Audit_Table
        VALUES (:OLD.Fee, :OLD.Copy_id, :OLD.Cus_id, :OLD.B_Date, :OLD.Cus_evo);
        -- I have replaced column names from other tables with column names 
        -- from table "Borrow"
   END;
   /
   

这是一个演示：

DEMO

在这个演示中我删除了

CONSTRAINT fk_Borrow_Copy_id_FK FOREIGN KEY (Copy_id) REFERENCES Copy(Copy_id),

来自表借用规范，因为它引用了我们在您的问题中没有的表副本。

在阅读了@Belayer 的评论后，我得出结论，您将需要两个这样的触发器：

CREATE OR REPLACE TRIGGER "AUDIT_TRIGGER"
BEFORE INSERT ON Borrow
FOR EACH ROW
when (new.Cus_evo = 0) 
BEGIN
    INSERT INTO Audit_Table
    VALUES (:new.Copy_id, :new.Copy_id, :new.B_Date, :new.Cus_id, :new.Cus_evo);
END;
/

CREATE OR REPLACE TRIGGER "AUDIT_TRIGGER2"
BEFORE UPDATE ON Borrow
FOR EACH ROW
when (OLD.Cus_evo = 0) 
BEGIN
    INSERT INTO Audit_Table
    VALUES (:OLD.Copy_id, :OLD.Copy_id, :OLD.B_Date, :OLD.Cus_id, :OLD.Cus_evo);
END;
/

这是一个带有演示的演示：

DEMO