vb_nima
شنبه 08 اسفند 1388, 01:32 صبح
کی همچین حرفی زده ؟ البته به نظر من هم بهتره از ObjectDataSource استفاده کنید، ولی فکر می کنم دوستمون کد Markup رو با HTML اشتباه گرفتن. کدهایی که در صفحه Aspx قرار می گیرن، ترکیبی از HTML و کدهای سمت سرور هستن. پس کدهای Sql به هیچ وجه در HTML قرار نمی گیرن.
دوست عزيز من بيشتر منطورم اين بود كه كدهاي دسترسي به داده در لايه Persentation نبايد قزار بگيرد كه لايه Perensention همون صفحات aspx هست. و فقط در اين صفحات ارجاع به لايه دسترسي به داده بايد انجام گيرد.
به اين قسمت توجه كنيد:
The data source controls, like any other ASP.NET control, have a corresponding declarative markup that is inserted into the ASP.NET page's HTML section. The markup below shows the complete markup for the page shown in Figure 4. Notice that we did not need to write a single line of server-side code in order to display data from a database.
<%@ Page Language="C#" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN"
"http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<script runat="server">
</script>
<html >
<head runat="server">
<title>Untitled Page</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:SqlDataSource ID="productsDataSource" Runat="server"
"SelectCommand="SELECT [ProductID], [ProductName], " & _
"[QuantityPerUnit], [UnitPrice], [UnitsInStock] " & _
"FROM [Products]"
ConnectionString=
"<%$ ConnectionStrings:NWConnectionString %>"
DataSourceMode="DataReader">
</asp:SqlDataSource>
<asp:GridView ID="productGridView" Runat="server"
DataSourceID="productsDataSource"
DataKeyNames="ProductID" AutoGenerateColumns="False">
<Columns>
<asp:BoundField ReadOnly="True"
HeaderText="ProductID" InsertVisible="False"
DataField="ProductID"
SortExpression="ProductID"></asp:BoundField>
<asp:BoundField HeaderText="ProductName"
DataField="ProductName"
SortExpression="ProductName"></asp:BoundField>
<asp:BoundField HeaderText="QuantityPerUnit"
DataField="QuantityPerUnit"
SortExpression="QuantityPerUnit"></asp:BoundField>
<asp:BoundField HeaderText="UnitPrice"
DataField="UnitPrice" SortExpression="UnitPrice">
</asp:BoundField>
<asp:BoundField HeaderText="UnitsInStock"
DataField="UnitsInStock"
SortExpression="UnitsInStock"></asp:BoundField>
</Columns>
</asp:GridView>
</div>
</form>
</body>
</html>
Accessing Data with the ObjectDataSource
With the SqlDataSource control, the ASP.NET page contains the specific details pertinent to data access. That is, buried in the SqlDataSource's declarative syntax you'll find a reference to a connection string, SQL statements for (potentially) SELECTs, INSERTs, UPDATEs, and DELETEs, and a list of parameters for each type of SQL statement. The downside of this approach is that it tightly binds the details of the data store to the ASP.NET page. If your database's underlying schema changes you'll have to modify all ASP.NET pages that touch the modified parts of the data store. Additionally, placing data access logic in the ASP.NET page increases the complexity of the pages. The data store's schema in your application may be large and particularly unwieldy to developers new to the project. By tying the data access logic to the ASP.NET page, these developers must have an intimate understanding of the data model and its relation to the program in order to create or modify ASP.NET pages.
A better approach for large Web applications is to divide the application's architecture into different layers. Typically Web applications are divided into three layers:
A Presentation Layer, which contains the ASP.NET Web pages.
A Data Access Layer (DAL), which consists of classes that serve as a ferry between the requests from the presentation layer and the backend data store layer.
A Data Store Layer, such as a Microsoft SQL Server database.
منبع: http://msdn.microsoft.com/en-us/library/aa479341.aspx