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asp.net try, catch, finally, Exception example: how to handle error

asp.net try, catch, finally, Exception example: how to handle error
ErrorHandlingExample.aspx
<%@ Page Language="C#" %>
<%@ Import Namespace="System.Data" %>
<%@ Import Namespace="System.Data.SqlClient" %>
<%@ Import Namespace="System.Configuration" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<script runat="server">
    protected void DropDownList1_SelectedIndexChanged(object sender, System.EventArgs e)
    {
        string selectSql = "SELECT ProductID, ProductName, UnitPrice FROM Products ";
        selectSql += "Where CategoryID=" + DropDownList1.SelectedValue;

        SqlConnection myConnection = new SqlConnection();
        myConnection.ConnectionString = ConfigurationManager.ConnectionStrings["NorthwindConnectionString"].ConnectionString;
        SqlCommand myCommand = new SqlCommand(selectSql,myConnection);
        SqlDataReader myReader;

        try
        {
            myConnection.Open();
            myReader = myCommand.ExecuteReader();

            GridView1.DataSource = myReader;
            GridView1.DataBind();
        }
        catch (Exception err)
        {
            Label1.Text = "Error: " + err.ToString();
        }

        finally 
        {
            myConnection.Close();
        }

    }
</script>

<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
    <title>asp.net try, catch, finally, Exception example: how to handle error</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <h2 style="color:Red">Example: Error Handling</h2>
        <asp:DropDownList 
            ID="DropDownList1"
            runat="server"
            DataSourceID="SqlDataSource1"
            DataTextField="CategoryName"
            DataValueField="CategoryID"
            AutoPostBack="true"
            OnSelectedIndexChanged="DropDownList1_SelectedIndexChanged"
            BackColor="CornflowerBlue"
            ForeColor="AliceBlue"
            >
        </asp:DropDownList>
        <asp:SqlDataSource 
            ID="SqlDataSource1"
            runat="server"
            ConnectionString="<%$ ConnectionStrings:NorthwindConnectionString %>"
            SelectCommand="SELECT CategoryID, CategoryName FROM Categories"
            >
        </asp:SqlDataSource>
        <br /><br />
        <asp:Label ID="Label1" runat="server" ForeColor="Red" Font-Italic="true">
        </asp:Label>
        <asp:GridView 
            ID="GridView1"
            runat="server"
            BackColor="CornflowerBlue"
            ForeColor="AliceBlue"
            BorderColor="LightBlue"
            Font-Italic="true"
            GridLines="Horizontal"
            HeaderStyle-BackColor="DarkBlue"
            HeaderStyle-ForeColor="White"
            HeaderStyle-Font-Italic="false"
            >
        </asp:GridView>
    </div>
    </form>
</body>
</html>








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