Access data layer study notes.

 

INSERT INTO [Products] ([ProductName], [SupplierID], [CategoryID], [QuantityPerUnit], [UnitPrice], [UnitsInStock], [UnitsOnOrder], [ReorderLevel], [Discontinued]) VALUES (@ProductName, @SupplierID, @CategoryID, @QuantityPerUnit, @UnitPrice, @UnitsInStock, @UnitsOnOrder, @ReorderLevel, @Discontinued);

SELECT SCOP_IDENTITY(); 

----which will return the last identity value inserted into an IDENTITY column in the same scope. (See the technical documentation for more information about SCOPE_IDENTITY()

public partial class Northwind
{
    public partial class SuppliersRow
    {
        public Northwind.ProductsDataTable GetProducts()
        {
            ProductsTableAdapter productsAdapter = new ProductsTableAdapter();
           return productsAdapter.GetProductsBySupplierID(this.SupplierID);
        }
    }
}

<ItemTemplate>
                            <asp:BulletedList ID="BulletedList1" runat="server" DataSource='<%# ((Northwind.SuppliersRow)((System.Data.DataRowView) Container.DataItem).Row).GetProducts() %>'
                                    DataTextField="ProductName">
                            </asp:BulletedList>
                        </ItemTemplate>

We define a function GetProducts in class SuppliersRow which is generater by vs automately , but this sample add a function . this amazing me . 

 let us analyse how to use this function in typed dataset(强类型)。 because this is function is use in class Northwind.SuppliersRow , so in the Html we have to convert it to this type .but I also want to know how to got the data , we must learn form this ((Northwind.SuppliersRow)((System.Data.DataRowView) Container.DataItem).Row).GetRowducts().

many knowledage I need to master .

delete and update nonqury retrun type will return a int value  reprents the numuber of row it affect .

insert  although it will return a value , but the bype is boject . I must take caer of this.

nonqury retrun type is int .

scalar return type is object .

that's all , I know all about this , nothing have to doubt.