SQL Server创建销售订单触发器

Question

我真的想知道如何使用这些项创建触发器。 我有这6个表，我想知道如何创建销售订单触发器。 Extendedprice来自（sizeprice * quantity）+ ExtratoppingPrice 我希望触发器在order_item中插入Extendedprice的值。 非常感谢帮助我解决这些困难的任何人T ^ T

Create TABLE CUSTOMER(
    CustomerID          int         NOT NULL,
    CustomerFirstName   char(40)    NOT NULL, 
    CustomerLastName    char(40)    NOT NULL,
    Email               char(40)    NOT NULL,
    CustomerAddress     char(100)   NOT NULL,
    Phone           char(20)    NOT NULL,

    CONSTRAINT     CUSTOMER_PK  PRIMARY KEY (CustomerID)
);  

Create TABLE BASE_TYPE(
    BaseCode        int           NOT NULL,
    BaseDescription     char(40)      NOT NULL

    CONSTRAINT  BASE_TYPE_PK    PRIMARY KEY (BaseCode)
);  


Create TABLE PIZZA_SIZE(
    SizeCode   int           NOT NULL,
    SizeType   char(10)      NOT NULL,
    SizePrice  numeric(10,2) NOT NULL,  
    CONSTRAINT  PIZZA_SIZE_PK   PRIMARY KEY (SizeCode)
);  

Create TABLE EXTRA_TOPPING(
    ExtraToppingCode     int           NOT NULL,
    ExtraToppingDetail   char(20)      NOT NULL,
    ExtraToppingPrice    numeric(10,2) NOT NULL

    CONSTRAINT  EXTRA_TOPPING_PK PRIMARY KEY(ExtraToppingCode)
);  


CREATE TABLE PIZZA(
    PizzaID      int        NOT NULL,  
    PizzaTopping char(40)   NOT NULL,
    BaseCode     int        NOT NULL,
    SizeCode     int        NOT NULL,
    CONSTRAINT  PIZZA_PK       PRIMARY KEY (PizzaID),
    CONSTRAINT  BASE_TYPE_FK1  FOREIGN KEY (BaseCode)
                       REFERENCES  BASE_TYPE(BaseCode)
                       ON UPDATE CASCADE
                       ON DELETE NO ACTION,
    CONSTRAINT  PIZZA_SIZE_FK    FOREIGN KEY (SizeCode)
                         REFERENCES  PIZZA_SIZE(SizeCode)
                             ON UPDATE CASCADE
                         ON DELETE NO ACTION
);

Create TABLE SALES_ORDERS(
    SalesOrderNumber    int         NOT NULL,
    CustomerID          int         NOT NULL,
    OrderDate           datetime    NOT NULL,  
    CONSTRAINT  SALES_ORDERS_PK PRIMARY KEY (SalesOrderNumber),
    CONSTRAINT  CUSTOMER_FK1    FOREIGN KEY (CustomerID)
                        REFERENCES  CUSTOMER(CustomerID)
                        ON UPDATE CASCADE
                        ON DELETE NO ACTION,
                        );


CREATE TABLE ORDER_ITEM(
    SalesOrderNumber    int           NOT NULL,
    PizzaID         int           NOT NULL,
    ExtraToppingCode    int           NULL,
    Quantity        numeric       NOT NULL,
    ExtendedPrice       numeric(10,2) NULL,

    CONSTRAINT  ORDER_ITEM_PK1 PRIMARY KEY (SalesOrderNumber,PizzaID),
    CONSTRAINT  ORDER_ITEM_FK1   FOREIGN KEY (SalesOrderNumber)
                         REFERENCES     SALES_ORDERS(SalesOrderNumber)
                         ON UPDATE NO ACTION
                         ON DELETE NO ACTION,
    CONSTRAINT  ORDER_ITEM_FK2      FOREIGN KEY (PizzaID)
                            REFERENCES      PIZZA(PizzaID)
                            ON UPDATE CASCADE
                            ON DELETE NO ACTION,
    CONSTRAINT  ORDER_ITEM_FK3      FOREIGN KEY (ExtraToppingCode)
                            REFERENCES      EXTRA_TOPPING(ExtraToppingCode)
                            ON UPDATE CASCADE
                            ON DELETE NO ACTION  
                            );