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私のデータベースには、Item、Ingredients、ItemContains、BillItem というテーブルがあります。アイテムは 1 つ以上の成分で「作られ」、テーブル ItemContains (IDItem - IDIngredient - ContainingQuantity) に表示されます。Quantity (BillItemQuantity) フィールドを持つ BillItem にレコードを挿入するとき、Trigger または StoredProcedure で Ingredient テーブルの Quantity フィールドの値を減らしたい

(IngredientQuantity = IngredientQuantity - BillItemQuantity*ContainingQuantity) ,

しかし問題は、Item に複数の Ingredient が含まれている場合です。IDIngredient をどこに配置すればよいかわかりません。一時テーブルで試してみましたが、失敗しました。私はOracle Database用のPL/SQLトリガーを書きましたが、うまくいきました。それをSQL Serverプロシージャなどに「変換」するのを手伝ってくれる人がいれば、とても感謝しています。ありがとう。

create or replace 
trigger ReduceQuantity
before insert on BillItem
for each row
declare
  quaN BillItem.Quantity%type;
  quaO BillItem.Quantity%type;
  idIt integer;
  idItOld integer;
  type RecCon is record (IngID ItemContains.idIngredient%type, Qua ItemContains.quantity%type);
  type TableQuantity is table of RecCon index by binary_integer;
  i binary_integer:=0;

  TabQuant TableQuantity;

begin
  idIt:= :New.IDItem;
  idItOld:= :Old.IDItem;
  quaN := :New.Quantity;
  kolS := :Old.Quantity;

  for rec in (select IDIngredient, Quantity from ItemContains where IDItem = idIt) loop
    TabQuant(i).IngID := rec.IDIngredient;
    TabKol(i).Qua := rec.Quantity;
    i:=i+1;
  end loop;

  if inserting then 
    i:=TabQuant.first;
    while i<=TabQuant.last loop
            update Ingredient set Quantity=Quantity-TabQuant(i).Qua*quaN where IDIngredient = TabQuant(i).IngID;
           i:=TabKol.Next(i);
    end loop; 

  end if;
end ReduceQuantity;

SQL Fiddle で実行できるスクリプト全体を次に示します。短縮されていますが、この問題に対して完全に機能します。したがって、新しい BillItem を挿入するときに Ingredient テーブルの数量を減らすトリガーが必要です (例: BillItem の 2 つのカプチーノは、「エスプレッソ コーヒー」を 2 個、「ミルク」を 0.10 l に減らします)

create table Item(
    IDItem integer NOT NULL,
    Name varchar(30) NOT NULL,
    ItemType varchar(9),
    Unit varchar(5) NOT NULL,
    Price decimal(5,2),
    CONSTRAINT item_PK PRIMARY KEY (IDItem),
    CONSTRAINT item_UQ UNIQUE (Name),
    CONSTRAINT item_unit_CHK CHECK (Unit in ('g', 'kg', 'ml', 'dl', 'l', 'pc')),
    CONSTRAINT item_type_CHK CHECK (ItemType in ('Food', 'Beverage'))
    );

create table Ingredient(
    IDIngredient integer NOT NULL,
    Name varchar(30) NOT NULL,
    Type varchar(9),
    Unit varchar(5) NOT NULL,
    IngredientQuantity decimal(6,2),
    CONSTRAINT ingredient_PK PRIMARY KEY (IDIngredient),
    CONSTRAINT ingredient_UQ UNIQUE (Name),
    CONSTRAINT ingredient_unit_CHK CHECK (Unit in ('g', 'kg', 'ml', 'dl', 'l', 'pc')),
    CONSTRAINT ingredient_type_CHK CHECK (TipSastojka in ('Food', 'Beverage')),
    CONSTRAINT ingredient_UQ1 CHECK(IngredientQuantity>=0)
);

create table ItemContains(
    IDItem integer NOT NULL,
    IDIngredient integer NOT NULL,
    ContainsQuantity decimal(4,2) NOT NULL,
    CONSTRAINT ItemContains_PK PRIMARY KEY (IDItem, IDIngredient),
    CONSTRAINT ItemContains_FK1 FOREIGN KEY (IDItem) references Item(IDItem),
    CONSTRAINT ItemContains_FK2 FOREIGN KEY (IDIngredient) references Ingredient(IDIngredient)
    );

create table Bill(
    IDBill integer NOT NULL,
    BillDate varchar(12) NOT NULL,
    TotalPrice decimal(8,2),
    CONSTRAINT bill_PK PRIMARY KEY (IDBill)
    );


create table BillItem(
    IDBillItem integer NOT NULL,
    IDBill integer NOT NULL,
    IDItem integer NOT NULL,
    BillItemQuantity decimal(3,1),
    CONSTRAINT billitem_PK PRIMARY KEY (IDBillItem),
    CONSTRAINT billitem_FK1 FOREIGN KEY (IDItem) references Item(IDItem),
    CONSTRAINT billitem_FK2 FOREIGN KEY (IDBill) references bill(IDBill)
);


Insert into Ingredient values(1, 'Amstel draft', 'Beverage', 'l', 100);
Insert into Ingredient values(2, 'Espresso coffee', 'Beverage', 'pc', 275);
Insert into Ingredient values(3, 'Milk', 'Beverage', 'l', 90);

Insert into Item values(1, 'Amstel - small', 'Beverage', 'l', 5);
Insert into Item values(2, 'Amstel - large', 'Beverage', 'l', 7);
Insert into Item values(3, 'Espresso', 'Beverage', 'pc', 4.5);
Insert into Item values(4, 'Cappuccino', 'Beverage', 'pc', 5.5);

Insert into ItemContains(IDItem, IDIngredient,ContainsQuantity) values(1, 1, 0.3);
Insert into ItemContains(IDItem, IDIngredient,ContainsQuantity) values(2, 1, 0.5);
Insert into ItemContains(IDItem, IDIngredient,ContainsQuantity) values(3, 2, 1);
Insert into ItemContains(IDItem, IDIngredient,ContainsQuantity) values(4, 2, 1);
Insert into ItemContains(IDItem, IDIngredient,ContainsQuantity) values(4, 3, 0.05);

insert into Bill values(1, '12-jun-2013', null);

Insert into BillItem(IDBillItem, IDBill, IDItem, BillItemQuantity) values(1, 1, 1, 3);
Insert into BillItem(IDBillItem, IDBill, IDItem, BillItemQuantity) values(2, 1, 2, 1);
Insert into BillItem(IDBillItem, IDBill, IDItem, BillItemQuantity) values(3, 1, 3, 1);
Insert into BillItem(IDBillItem, IDBill, IDItem, BillItemQuantity) values(4, 1, 4, 2);


CREATE VIEW ItemsIngredientsView  AS 
  select sa.IDItem as "ID Item",  art.Name as "Item name", sa.ContainsQuantity as "Quantity", s.Unit as "Unit", s.IDIngredient as "ID Ingredient", s.Name as "Ingredient name" from ItemContains sa left join Ingredient s on sa.IDIngredient=s.IDIngredient left join Item art on art.IDItem = sa.IDItem;

CREATE VIEW BillView AS 
  select r.IDBill as "Bill", sr.IDItem as "ID Item", art.Name as "Item Name", sr.BillItemQuantity as "Quantity", art.Price as "Price" from Bill r right join BillItem sr on r.IDBill=sr.IDBill left join Item art on sr.IDItem = art.IDItem;

CREATE VIEW BillTotalPriceView AS 
  select sum(sr.BillItemQuantity*art.Price) as "TotalPrice" from Bill r right join BillItem sr on r.IDBill=sr.IDBill left join Item art on sr.IDItem = art.IDItem;
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