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Scope

The aim of this tutorial is to offer you a jump start into using .Net technologies, in particular how to read trough a web form using a datagrid and some C# code.
In fact, ASP.NET controls such as datagrid allow developers to design quick aspx pages for simple tasks, but usually time consuming, such query and printing the result of a database query.

In this example I will use some C# code and a datagrid control to produce a web page with a simple but stylish results of a Sql query. The compressed file datgrid.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\datagrid where it is possible executing an aspx page and reading on Access database. So before beginning, remember you may need to grant these privileges to the aspx page (executing) and Access database (reading).

Suggestions

Maybe the best way to learn this tutorial is:

Extract the zip file in a directory as c:\inetpub\wwwroot\datagrid
Let your browser request the page datagrid.aspx (something as http://localhost/datagrid/datagrid.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 datagrid.aspx listing 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

Books table

First of all, let's make sure you have the mydatabase.mdb Access file, located somewhere such as c:\inetpub\wwwroot\datagrid, 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\datgrid the file datagrid.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" %>

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 Datagrid Web Control, as you can see there is a comment on top of most relevant line of code:

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 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();
//Trough the propriety DataSource web control mydatagrid acquires data values
mydatagrid.DataSource = reader;
//Trough web control datagrid, the data is being scrolled
mydatagrid.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 datagrid

As stated above, in this example, it we use the web control datagrid because it really makes easy publish Sql results in a nice and formatted Html table with some Css style.
In fact, for this basic example we just need of the following code:

<asp:DataGrid id="mydatagrid" runat="server"
BorderColor="blue"
BorderWidth="1"
CellPadding="3"
Font-Name="Verdana"
Font-Size="8pt" AutoGenerateColumns="true">
<HeaderStyle BackColor="#aaaadd">
</HeaderStyle>
</asp:DataGrid>

The property BorderColor,BorderWidth,CellPadding, Font-Name="Verdana", Font-Size="8pt" refers to the layout of the datagrid. You may try to change them with different colour, width, font face and size, etc.
The property AutoGenerateColumns="true" is true anyway by default, it means that the data grid scrolls of the columns of the queried recordset, otherwise, if you se the value to false you need a control for each column. In this example we simply want all the data easy and quick so we just define the colour of the HeaderStyle and request the page in a browser. The page should look something as this:

Final output

Was it quick?

Downloads:
datgrid.zip ( 10 KB)

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