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Scope

This tutorial is meant to give you a jump start into using .Net technologies, in particular how to read and write data trough a web form and some C# code.
The practical aim is writing a simple web page that allows to read and save data the entry for our on line bookstore in a Microsoft Access database. The compressed file bookstore.zip contains source of the web page and the database.

Requirements

To practice with the following example you need of a web server such as Microsoft Internet Information Server (IIS) running .Net framework. It means that on your local web path you set up a folder such as c:\inetpub\wwwroot\bookstore where it is possible executing an aspx page and reading and writing Access database. So before to start remember you may need to grant this privileges to the aspx page (executing) and Access database (reading and writing).

Suggestions

Maybe the best way to learn this tutorial is:

Extract the zip file in a directory as c:\inetpub\wwwroot\bookstore
Let your browser request the page list_insert_books.aspx (something as http://localhost/bookstore/list_insert_books.aspx), if errors occur probably it means you need to grant the necessary privileges as above mentioned
Create an new page (as exercise.aspx) when you have list_insert_books.aspx listing and inserting book data
After reading each paragraph, copy and paste the code in the grey box in your new page exercise.aspx
You just need to copy at the begin the file the language and namespace directives, including the style sheet file, the C# code within the <script runat="server"> .... </script> and last the web Repeat and Form controls.
When you have finish copying check the page on your browser, probably the .Net Framework Engine will display some Compilation Error, it means probably you have made some errors while copying the code. Well, you always learn by mistakes, fix them and make your page fly

Guestbook table

First of all, let’s make sure you have the mydatabase.mdb Access file, located somewhere such as c:\inetpub\wwwroot\bookstore, containing the books table with the following columns:

id (counter)
title (text)
author (text)
pyear (integer)
price (currency)

For the sake of the example 2 rows have been inserted:
The Missing World, Margot Livesey, 2000
The King is Dead, Jim Lewis, 2003
The books table should look something like this:

Access Table

Extracting and printing the data

In c:\inetpub\wwwroot\bookstore the file list_insert_books.aspx contains all the code we need. To achieve our first task, we need C# function that connects to the database and queries and pass the data to a Web Control.
At the top of the page, we need to specify the language used and to import the necessary Namespace (class) containing the OleDb objects we need for database interaction.

<%@ Page Language="C#" Debug="true" %>
<%@ Import Namespace="System.Data.OleDb" %>

The page includes also a style sheet file, also provided in the zip file:

For any C# aspx page the .Net Framework looks for the start-up function Page_Load() that, in our case, calls the function ScrollData().

ScrollData() 's duty is to query and to pass the data the Repeater Web Control:

private void ScrollData()
{
//Creation object OleDbConnection
OleDbConnection conn = null;
OleDbDataReader reader = null;
//Construct try/catch
//If something goes bad the catch expression will handle

try
{
//The connection string to the mydatabase.mdb, located in the same folder of this script
string strconn = "Provider=Microsoft.Jet.OLEDB.4.0; Data Source=" + Server.MapPath("mydatabase.mdb");
//Setting up the object conn
conn = new OleDbConnection(strconn);
//Opening the connection
conn.Open();
//Making up the sql string
string myquery = "SELECT title,author,pyear,price,date_ins FROM books ORDER BY title";
//Setting up the OleDbCommand
OleDbCommand cmd = new OleDbCommand(myquery, conn);
//Trough the element ExecuteReader(SqlCommand) the query results to the OleDbDataReader
reader = cmd.ExecuteReader();
//Trought the propriety DataSource web control Repeater acquires data values
myrepeater.DataSource = reader;
//Trought web control Reapeter is being scrolled
myrepeater.DataBind();
}

//the catch construct in case connection, query or else goes wrong prints the relative error message
catch (Exception e)
{
Response.Write(e.Message);
Response.End();
}

finally
{
// always call Close when done reading.
if (reader != null) reader.Close();
if (conn != null) conn.Close();
}

}

Web Control Repeater

In this example, it we use the web control Repeater becouse is very flexible and easy implemented with html and Css.
In fact, the last lines of ScrollData code referring to a Repeater Web Control defined by the following code:

<asp:Repeater ID= "myrepeater" Runat= "server">

<SeparatorTemplate>
<p align="center">*****</p>
</SeparatorTemplate>

<ItemTemplate>
<div class="Item">
<i>
<%# DataBinder.Eval(Container.DataItem, "title") %>
</i>
<strong>
<%# DataBinder.Eval(Container.DataItem, "author") %>
</strong>,
<%# DataBinder.Eval(Container.DataItem, "pyear") %>
<br/>
€
<%# DataBinder.Eval(Container.DataItem, "price") %>
<br/>
</div>
</ItemTemplate>

</asp:Repeater>

The property SeparatorTemplate allows to define the html output between the items (the data rows).
The property ItemTemplate through the databinding of the columns of displays each row within a <div class="Item">. The Css class Item is defined in the included file somestyle.css.
Anyhow, the core Asp.net tag is <%# DataBinder.Eval(Container.DataItem, column name) %>: it prints the data retrieved by the c# function ScrollData().
Since we manually inserted some rows the page should display an output as following:

The King is Dead Jim Lewis,2003
€:9

*****

The Missing World, Margot Livesey,2000
€:12

If you did not get any errors, you are ready to move to the second part Web controls and C# Sharp (Part II) saving data in an Access database using a web form .

1-Web controls and C# Sharp (Part I) | 2-Web controls and C# Sharp (Part II) |

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