Dynamically add and delete rows from ASP.Net GridView on Button click using C#

Hi irshad1231,

I have modified the code. Check this example. Now please take its reference and correct your code.

HTML

<asp:GridView ID="Gridview1" runat="server" ShowFooter="true" AutoGenerateColumns="false"
    OnRowCreated="Gridview1_RowCreated">
    <Columns>
        <asp:BoundField DataField="RowNumber" HeaderText="Row Number" />
        <asp:TemplateField HeaderText="Header 1">
            <ItemTemplate>
                <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
            </ItemTemplate>
        </asp:TemplateField>
        <asp:TemplateField HeaderText="Header 2">
            <ItemTemplate>
                <asp:TextBox ID="TextBox2" runat="server"></asp:TextBox>
            </ItemTemplate>
        </asp:TemplateField>
        <asp:TemplateField HeaderText="Header 3">
            <ItemTemplate>
                <asp:TextBox ID="TextBox3" runat="server"></asp:TextBox>
            </ItemTemplate>
            <FooterStyle HorizontalAlign="Right" />
            <FooterTemplate>
                <asp:Button ID="ButtonAdd" runat="server" Text="Add New Row" OnClick="ButtonAdd_Click" />
            </FooterTemplate>
        </asp:TemplateField>
        <asp:TemplateField>
            <ItemTemplate>
                <asp:LinkButton ID="LinkButton1" runat="server" OnClick="LinkButton1_Click">Remove</asp:LinkButton>
            </ItemTemplate>
        </asp:TemplateField>
    </Columns>
</asp:GridView>
<asp:Button ID="Button1" runat="server" Text="Save" OnClick="Button1_Click" />

C#

private void SetInitialRow()
{
    DataTable dt = new DataTable();
    DataRow dr = null;
    dt.Columns.Add(new DataColumn("RowNumber", typeof(string)));
    dt.Columns.Add(new DataColumn("Column1", typeof(string)));
    dt.Columns.Add(new DataColumn("Column2", typeof(string)));
    dt.Columns.Add(new DataColumn("Column3", typeof(string)));
    dr = dt.NewRow();
    dr["RowNumber"] = (int)ViewState["RowNumber"];
    dr["Column1"] = string.Empty;
    dr["Column2"] = string.Empty;
    dr["Column3"] = string.Empty;
    dt.Rows.Add(dr);
    //dr = dt.NewRow();

    //Store the DataTable in ViewState
    ViewState["CurrentTable"] = dt;

    Gridview1.DataSource = dt;
    Gridview1.DataBind();
}
private void AddNewRowToGrid()
{
    int rowIndex = 0;

    if (ViewState["CurrentTable"] != null)
    {
        DataTable dtCurrentTable = (DataTable)ViewState["CurrentTable"];
        DataRow drCurrentRow = null;
        if (dtCurrentTable.Rows.Count > 0)
        {
            for (int i = 1; i <= dtCurrentTable.Rows.Count; i++)
            {
                //extract the TextBox values
                TextBox box1 = (TextBox)Gridview1.Rows[rowIndex].Cells[1].FindControl("TextBox1");
                TextBox box2 = (TextBox)Gridview1.Rows[rowIndex].Cells[2].FindControl("TextBox2");
                TextBox box3 = (TextBox)Gridview1.Rows[rowIndex].Cells[3].FindControl("TextBox3");

                drCurrentRow = dtCurrentTable.NewRow();

                drCurrentRow["RowNumber"] = (int)ViewState["RowNumber"] + 1;
                drCurrentRow["Column1"] = box1.Text;
                drCurrentRow["Column2"] = box2.Text;
                drCurrentRow["Column3"] = box3.Text;
                rowIndex++;
            }
            ViewState["RowNumber"] = (int)ViewState["RowNumber"] + 1;
            dtCurrentTable.Rows.Add(drCurrentRow);
            ViewState["CurrentTable"] = dtCurrentTable;

            Gridview1.DataSource = dtCurrentTable;
            Gridview1.DataBind();
        }
    }
    else
    {
        Response.Write("ViewState is null");
    }

    //Set Previous Data on Postbacks
    SetPreviousData();
}
private void SetPreviousData()
{
    int rowIndex = 0;
    if (ViewState["CurrentTable"] != null)
    {
        DataTable dt = (DataTable)ViewState["CurrentTable"];
        if (dt.Rows.Count > 0)
        {
            for (int i = 1; i < dt.Rows.Count; i++)
            {
                TextBox box1 = (TextBox)Gridview1.Rows[rowIndex].Cells[1].FindControl("TextBox1");
                TextBox box2 = (TextBox)Gridview1.Rows[rowIndex].Cells[2].FindControl("TextBox2");
                TextBox box3 = (TextBox)Gridview1.Rows[rowIndex].Cells[3].FindControl("TextBox3");

                box1.Text = dt.Rows[i]["Column1"].ToString();
                box2.Text = dt.Rows[i]["Column2"].ToString();
                box3.Text = dt.Rows[i]["Column3"].ToString();

                rowIndex++;

            }
        }
        // ViewState["CurrentTable"] = dt;

    }
}
protected void Page_Load(object sender, EventArgs e)
{
    if (!Page.IsPostBack)
    {
        ViewState["RowNumber"] = 1;
        SetInitialRow();
    }
}
protected void ButtonAdd_Click(object sender, EventArgs e)
{
    AddNewRowToGrid();
}
protected void Button1_Click(object sender, EventArgs e)
{
    int rowIndex = 0;
    StringCollection sc = new StringCollection();
    if (ViewState["CurrentTable"] != null)
    {
        DataTable dtCurrentTable = (DataTable)ViewState["CurrentTable"];
        if (dtCurrentTable.Rows.Count > 0)
        {
            for (int i = 1; i <= dtCurrentTable.Rows.Count; i++)
            {
                //extract the TextBox values
                TextBox box1 = (TextBox)Gridview1.Rows[rowIndex].Cells[1].FindControl("TextBox1");
                TextBox box2 = (TextBox)Gridview1.Rows[rowIndex].Cells[2].FindControl("TextBox2");
                TextBox box3 = (TextBox)Gridview1.Rows[rowIndex].Cells[3].FindControl("TextBox3");

                //get the values from the TextBoxes
                //then add it to the collections with a comma "," as the delimited values
                sc.Add(box1.Text + "," + box2.Text + "," + box3.Text);
                rowIndex++;
            }
            //Call the method for executing inserts
            InsertRecords(sc);
        }
    }
}
//A method that returns a string which calls the connection string from the web.config
private string GetConnectionString()
{
    //"DBConnection" is the name of the Connection String
    //that was set up from the web.config file
    return System.Configuration.ConfigurationManager.ConnectionStrings["DBConnection"].ConnectionString;
}
//A method that Inserts the records to the database
private void InsertRecords(StringCollection sc)
{
    SqlConnection conn = new SqlConnection(GetConnectionString());
    StringBuilder sb = new StringBuilder(string.Empty);
    string[] splitItems = null;
    foreach (string item in sc)
    {

        const string sqlStatement = "INSERT INTO SampleTable (Column1,Column2,Column3) VALUES";
        if (item.Contains(","))
        {
            splitItems = item.Split(",".ToCharArray());
            sb.AppendFormat("{0}('{1}','{2}','{3}'); ", sqlStatement, splitItems[0], splitItems[1], splitItems[2]);
        }

    }

    try
    {
        conn.Open();
        SqlCommand cmd = new SqlCommand(sb.ToString(), conn);
        cmd.CommandType = CommandType.Text;
        cmd.ExecuteNonQuery();

        Page.ClientScript.RegisterClientScriptBlock(typeof(Page), "Script", "alert('Records Successfuly Saved!');", true);

    }
    catch (System.Data.SqlClient.SqlException ex)
    {
        string msg = "Insert Error:";
        msg += ex.Message;
        throw new Exception(msg);

    }
    finally
    {
        conn.Close();
    }
}
// Hide the Remove Button at the last row of the GridView
protected void Gridview1_RowCreated(object sender, GridViewRowEventArgs e)
{
    if (e.Row.RowType == DataControlRowType.DataRow)
    {
        DataTable dt = (DataTable)ViewState["CurrentTable"];
        LinkButton lb = (LinkButton)e.Row.FindControl("LinkButton1");
        if (lb != null)
        {
            if (dt.Rows.Count > 1)
            {
                if (e.Row.RowIndex == dt.Rows.Count - 1)
                {
                    lb.Visible = false;
                }
            }
            else
            {
                lb.Visible = false;
            }
        }
    }
}
protected void LinkButton1_Click(object sender, EventArgs e)
{
    LinkButton lb = (LinkButton)sender;
    GridViewRow gvRow = (GridViewRow)lb.NamingContainer;
    int rowID = gvRow.RowIndex + 1;
    if (ViewState["CurrentTable"] != null)
    {
        DataTable dt = (DataTable)ViewState["CurrentTable"];
        if (dt.Rows.Count > 1)
        {
            if (gvRow.RowIndex < dt.Rows.Count - 1)
            {
                //Remove the Selected Row data
                dt.Rows.Remove(dt.Rows[rowID]);
            }
        }
        //Store the current data in ViewState for future reference
        ViewState["CurrentTable"] = dt;
        //Re bind the GridView for the updated data
        Gridview1.DataSource = dt;
        Gridview1.DataBind();
    }

    //Set Previous Data on Postbacks
    SetPreviousData();
}

Screenshot