Задача на Transact-SQL

[REztor]

Помогите написать в Transact-SQL:
функция расчета товара в товарном документе ( Товары_и_товарный документ_E10
Quantity_of_the_goods(Количество товара) *Cost_price(Отпускная_цена) )чтобы выводила окончательную цену

Триггер автоматического продажи на склад (при продажи товара количество товара ументшается на складе(CREATE TABLE Товар_E2 Quantity_of_the_goods_in_a_warehous e(Количество товара_на_складе)

[REztor]

CREATE TABLE Группа_E1
(
        Group_number integer  NOT NULL ,
        Supergroup integer NOT NULL ,
        Group_name varchar(20) NOT NULL ,
        CONSTRAINT XPKГруппа_E1 PRIMARY KEY (Group_number ASC),
        CONSTRAINT  R_26 FOREIGN KEY (Supergroup) REFERENCES Группа_E1(Group_number)
)
go

CREATE TABLE Товар_E2
(
        Goods_article integer  NULL ,
        Goods_name varchar(30) NOT  NULL ,
        Quantity_of_the_goods_in_a_warehouse integer NOT NULL ,
        Number_of_the_certificate_of_quality_of_the_goods varbinary  NULL ,
        Goods_packing varchar(20)  NULL ,
        The_name_of_firm_of_the_manufacturer_of_the_goods varchar(30) NOT NULL ,
        Group_number integer  NOT NULL ,
        Goods_code integer  NOT NULL ,
        CONSTRAINT XPKТовар_E2 PRIMARY KEY (Group_number ASC,Goods_code ASC),
        CONSTRAINT  R_4 FOREIGN KEY (Group_number) REFERENCES Группа_E1(Group_number)
)
go

CREATE TABLE Товары_и_товарный_документ_E10
(
        Group_number integer  NOT NULL ,
        Goods_code integer  NOT NULL ,
        Number_of_the_commodity_document varchar(30)  NOT NULL ,
        Quantity_of_the_goods integer NOT NULL ,
        Cost_price integer NOT NULL ,
        Type_of_the_commodity_document varchar(30)  NOT NULL ,
        CONSTRAINT XPKТовары_и_товарный_документ_E10 PRIMARY KEY (Group_number ASC,Goods_code ASC,Number_of_the_commodity_document ASC,Type_of_the_commodity_document ASC),
        CONSTRAINT  R_15 FOREIGN KEY (Group_number,Goods_code) REFERENCES Товар_E2(Group_number,Goods_code),
   CONSTRAINT  R_14 FOREIGN KEY (Number_of_the_commodity_document,Type_of_the_commodity_document) REFERENCES Товарный_документ_E9(Number_of_the_commodity_document,Type_of_the_commodity_document)
)
go

CREATE TABLE Товарный_документ_E9
(
        Number_of_the_buyer integer  NOT NULL ,
        Number_of_the_commodity_document varchar(30)  NOT NULL ,
        Waybill1 varchar(30)  NULL ,
        Type_of_the_commodity_document varchar(30)  NOT NULL ,
        Waybill2 varchar(30)  NULL ,
        Date_of_sale_of_the_goods datetime NOT NULL ,
        Date_of_return_of_the_goods datetime  NULL ,
        Monetary_unit_code integer NOT NULL ,
        CONSTRAINT XPKТоварный_документ_E9 PRIMARY KEY (Number_of_the_commodity_document ASC,Type_of_the_commodity_document ASC),
        CONSTRAINT  R_27 FOREIGN KEY (Number_of_the_buyer) REFERENCES Покупатель_E3(Number_of_the_buyer),
    CONSTRAINT  R_16 FOREIGN KEY (Waybill1,Waybill2) REFERENCES Товарный_документ_E9(Number_of_the_commodity_document,Type_of_the_commodity_document)
)
go

CREATE TABLE Покупатель_E3
(
        Number_of_the_buyer integer  NOT NULL ,
        Type_of_the_buyer varchar(30) NOT NULL ,
        Phone_number integer  NULL ,
        CONSTRAINT XPKПокупатель_E3 PRIMARY KEY (Number_of_the_buyer ASC),

)
go

[REztor]

CREATE TABLE Юридическое_лицо_E4
(
        Number_of_the_buyer integer  NOT NULL ,
        Firm_name varchar(20)  NULL ,
        Legal_address varchar(20) NOT NULL ,
        License_number integer  NULL ,
        Bank_details integer  NULL ,
        Firm_category varchar(20)  NULL ,
        CONSTRAINT XPKЮридическое_лицо_E4 PRIMARY KEY (Number_of_the_buyer ASC),
        FOREIGN KEY (Number_of_the_buyer) REFERENCES Покупатель_E3(Number_of_the_buyer)
)
go

CREATE TABLE Частное_лицо_E5
(
        Number_of_the_buyer integer  NOT NULL ,
        Passport_number integer NOT NULL ,
        Surname_private_person varchar(20) NOT NULL ,
        Name_private_person varchar(20) NOT NULL ,
        Patronymic_private_person varchar(20)  NULL ,
        Year_of_birth datetime  NULL ,
        Address_private_person varchar(50) NOT NULL ,
        CONSTRAINT XPKЧастное_лицо_E5 PRIMARY KEY (Number_of_the_buyer ASC),
        FOREIGN KEY (Number_of_the_buyer) REFERENCES Покупатель_E3(Number_of_the_buyer)
)
go

CREATE TABLE Платежный_документ_E8
(
        Number_of_the_commodity_document varchar(30)  NOT NULL ,
        Type_of_the_payment_document varchar(30) NOT NULL ,
        Goods_identification integer  NULL ,
        Software_number_on_bank_identification varchar(20)  NULL ,
        Registration_date datetime NOT NULL ,
        Summa integer NOT NULL ,
        Monetary_unit_code integer  NOT NULL ,
        Type_of_the_commodity_document varchar(30)  NOT NULL ,
        CONSTRAINT XPKПлатежный_документ_E8 PRIMARY KEY (Number_of_the_commodity_document ASC,Type_of_the_commodity_document ASC),
        CONSTRAINT  R_13 FOREIGN KEY (Monetary_unit_code) REFERENCES Денежная_единица_E6(Monetary_unit_code),
    CONSTRAINT  R_31 FOREIGN KEY (Number_of_the_commodity_document,Type_of_the_commodity_document) REFERENCES Товарный_документ_E9(Number_of_the_commodity_document,Type_of_the_commodity_document)
)
go

CREATE TABLE Денежная_единица_E6
(
        Monetary_unit_code integer  NOT NULL ,
        Country varchar(20)  NULL ,
        CONSTRAINT XPKДенежная_единица_E6 PRIMARY KEY (Monetary_unit_code ASC),
        )
go

CREATE TABLE Курс_денежной_единицы_E7
(
        From_what integer  NOT NULL ,
        In_what integer  NOT NULL ,
        Date datetime  NOT NULL ,
        Value_of_a_course integer NOT NULL ,
        CONSTRAINT XPKКурс_денежной_единицы_E7 PRIMARY KEY (From_what ASC,In_what ASC,Date ASC),
        CONSTRAINT  R_29 FOREIGN KEY (From_what) REFERENCES Денежная_единица_E6(Monetary_unit_code),
    CONSTRAINT  R_30 FOREIGN KEY (In_what) REFERENCES Денежная_единица_E6(Monetary_unit_code)
)
go

[REztor]

Насчет цены, договоримся