Using Gridview Row Command Event fetch data on textbox on form

Step 1: Create web Page and Insert Following Control in Form tag:

<form id="form1" runat="server" >  
      Name&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
      <br />
      Mobile No <asp:TextBox ID="TextBox2" runat="server"></asp:TextBox>
      <br />
      Email Id&nbsp;&nbsp;&nbsp;&nbsp; <asp:TextBox ID="TextBox3" runat="server"></asp:TextBox>
      <br />
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
      <asp:Button ID="txt_Insert" runat="server" onclick="txt_Insert_Click"
          Text="Submit" />
      <br />
      <br />

Step 2:- Insert GridView and Connection with Table in Database

 <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False"
          DataKeyNames="Id" DataSourceID="SqlDataSource1"
          onrowcommand="GridView1_RowCommand">
          <Columns>
              <asp:TemplateField ShowHeader="False">
                  <EditItemTemplate>
                      <asp:LinkButton ID="LinkButton1" runat="server" CausesValidation="True"
                          CommandName="Update" Text="Update"></asp:LinkButton>
                      &nbsp;<asp:LinkButton ID="LinkButton2" runat="server" CausesValidation="False"
                          CommandName="Cancel" Text="Cancel"></asp:LinkButton>
                  </EditItemTemplate>
                  <ItemTemplate>
                      <asp:LinkButton ID="LinkButton1" runat="server" CausesValidation="False"
                          CommandName="Edits" CommandArgument ='<%# Bind("Id") %>' Text="Edit"></asp:LinkButton>
                  </ItemTemplate>
              </asp:TemplateField>
              <asp:TemplateField HeaderText="Id" InsertVisible="False" SortExpression="Id"
                  Visible="False">
                  <ItemTemplate>
                      <asp:Label ID="Label1" runat="server" Text='<%# Bind("Id") %>'></asp:Label>
                  </ItemTemplate>
              </asp:TemplateField>
              <asp:BoundField DataField="Name" HeaderText="Name" SortExpression="Name" />
              <asp:BoundField DataField="Mobile_No" HeaderText="Mobile_No"
                  SortExpression="Mobile_No" />
              <asp:BoundField DataField="Email_Id" HeaderText="Email_Id"
                  SortExpression="Email_Id" />
          </Columns>
      </asp:GridView>
      <asp:SqlDataSource ID="SqlDataSource1" runat="server"
          ConnectionString="<%$ ConnectionStrings:admin %>"
          DeleteCommand="DELETE FROM [Exam] WHERE [Id] = @Id"
          InsertCommand="INSERT INTO [Exam] ([Name], [Mobile_No], [Email_Id]) VALUES (@Name, @Mobile_No, @Email_Id)"
          SelectCommand="SELECT * FROM [Exam]"
          UpdateCommand="UPDATE [Exam] SET [Name] = @Name, [Mobile_No] = @Mobile_No, [Email_Id] = @Email_Id WHERE [Id] = @Id">
          <DeleteParameters>
              <asp:Parameter Name="Id" Type="Int64" />
          </DeleteParameters>
          <InsertParameters>
              <asp:Parameter Name="Name" Type="String" />
              <asp:Parameter Name="Mobile_No" Type="String" />
              <asp:Parameter Name="Email_Id" Type="String" />
          </InsertParameters>
          <UpdateParameters>
              <asp:Parameter Name="Name" Type="String" />
              <asp:Parameter Name="Mobile_No" Type="String" />
              <asp:Parameter Name="Email_Id" Type="String" />
              <asp:Parameter Name="Id" Type="Int64" />
          </UpdateParameters>
      </asp:SqlDataSource>
      </form>


Step 3 : Double Click On Button and insert Following Code on in .CS Page :-

Insert Code In Namespace On CS Page ....

using System.Data;
using System.Data.SqlClient;
using System.Configuration;

Connection With Database.....

SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["asprockers"].ConnectionString);

Code on Insert Button......

protected void txt_Insert_Click(object sender, EventArgs e)
    {
        if (con.State == ConnectionState.Open)
        {
            con.Close();
        }
        con.Open();
        SqlCommand cmd = new SqlCommand("insert into Exam(Name,Mobile_No,Email_Id) values(@Name,@Mobile_No,@Email_Id)", con);
        cmd.Parameters.AddWithValue("@Name", TextBox1.Text);
        cmd.Parameters.AddWithValue("@Mobile_No", TextBox2.Text);
        cmd.Parameters.AddWithValue("@Email_Id", TextBox3.Text);
        cmd.ExecuteNonQuery();
        con.Close();
        TextBox1.Text = "";
        TextBox2.Text = "";
        TextBox3.Text = "";
        GridView1.DataBind();
    }

Code on Gridview Row Command Event...

if (e.CommandName == "Edits")
        {
            string ss= e.CommandArgument.ToString();
            if (con.State == ConnectionState.Open)
            {
                con.Close();
            }
            SqlCommand cmd = new SqlCommand("select * from Exam where Id='" + ss.ToString() + "'", con);
            SqlDataAdapter da = new SqlDataAdapter(cmd);
            DataTable dt = new DataTable();
            da.Fill(dt);
            if (dt.Rows.Count > 0)
            {
                TextBox1.Text = dt.Rows[0]["Name"].ToString();
                TextBox2.Text = dt.Rows[0]["Mobile_No"].ToString();
                TextBox3.Text = dt.Rows[0]["Email_Id"].ToString();

            }