Database operation ASP.net using SQL Server 2000

The ADO.NET architecture is designed to make life easier for both the application developer and the database provider. To the developer, it presents a set of abstract classes that define a common set of methods and properties that can be used to access any data source. The data source is treated as an abstract entity, much like a drawing surface is to the GDI+ classes.

Controls :

• Three Textbox
• Three Button
• One GridView
• SqlDataSource

Setting Gridview : 

• Add Gridview select auto format if you want to use available style for gridview select a style click ok
• Choose data source select < New Data source.. >
• Select Database from Configuration Wizard 
• Click New Connection and change database type from Add Connection wizard
• Choose SQL Server click ok
• Enter Server name I have have used . for local client server
• Select Database Click ok
• Select check your connection string and click next
• Select your table and fields which you want to show on Gridview

Coding :
 SqlConnection con;
    SqlCommand com;
    protected void Page_Load(object sender, EventArgs e)
    {
        con = new SqlConnection("initial catalog=bsw;data source=.;integrated security=true");
        com = com = new SqlCommand();
        com.Connection = con;
    }



    protected void btnSave_Click(object sender, EventArgs e)
    {
        if (txtroll.Text == "" && txtname.Text == "" && txtcity.Text == "")
        {
            Label1.Text = "Please Fill all fields value";
        }
        else
        {
            try
            {
                con.Open();
                com.CommandText = "insert into stu values(" + txtroll.Text + ",'" + txtname.Text + "','" + txtcity.Text + "')";
                com.ExecuteNonQuery();
                Label1.Text = "";
                GridView1.DataBind();
            }
            catch (Exception ex)
            {
                Label1.Text = ex.Message;
            }
            finally
            {
                con.Close();
            }
        }
    }
    protected void btnUpdate_Click(object sender, EventArgs e)
    {
        try
        {
            if (txtroll.Text == "" && txtname.Text == "" && txtcity.Text == "")
            {
                Label1.Text = "Please provide all fields value";
            }
            else
            {
                con.Open();
                com.CommandText = "update stu set name='" + txtname.Text + "',city='" + txtcity.Text + "' where roll=" + txtroll.Text;
                com.ExecuteNonQuery();
                Label1.Text="";
                GridView1.DataBind();

            }
        }
        catch (Exception ex)
        {
            Label1.Text = ex.Message;
        }
        finally
        {
            con.Close();
        }
    }
    protected void btnDelete_Click(object sender, EventArgs e)
    {
        try
        {
            if (txtroll.Text == "" && txtname.Text == "" && txtcity.Text == "")
            {
                Label1.Text = "Please enter roll number";
                txtroll.Focus();
            }
            else
            {
                con.Open();
                com.CommandText = "delete from stu where roll=" + txtroll.Text;
                com.ExecuteNonQuery();
                GridView1.DataBind();
            }
        }
        catch (Exception ex)
        {
            Label1.Text = ex.Message;
        }
        finally
        {
            Label1.Text = con.Close();
        }

    }