Hi JennyD6856,
Refer below sample.
HTML
<asp:gridview ID="Gridview1" runat="server" ShowFooter="true" AutoGenerateColumns="false">
<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>
</Columns>
</asp:gridview>
Namespaces
C#
using System.Data;
VB.Net
Imports System.Data
Code
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"] = 1;
dr["Column1"] = string.Empty;
dr["Column2"] = string.Empty;
dr["Column3"] = string.Empty;
dt.Rows.Add(dr);
//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)
{
TextBox box1 = null;
TextBox box2 = null;
TextBox box3 = null;
for (int i = 1; i <= dtCurrentTable.Rows.Count; i++)
{
//extract the TextBox values
box1 = (TextBox)Gridview1.Rows[rowIndex].Cells[1].FindControl("TextBox1");
box2 = (TextBox)Gridview1.Rows[rowIndex].Cells[2].FindControl("TextBox2");
box3 = (TextBox)Gridview1.Rows[rowIndex].Cells[3].FindControl("TextBox3");
drCurrentRow = dtCurrentTable.NewRow();
drCurrentRow["RowNumber"] = i + 1;
dtCurrentTable.Rows[i - 1]["Column1"] = box1.Text;
dtCurrentTable.Rows[i - 1]["Column2"] = box2.Text;
dtCurrentTable.Rows[i - 1]["Column3"] = box3.Text;
rowIndex++;
}
DataRow[] dr = dtCurrentTable.Select("Column1 = '" + box1.Text + "' and Column2='" + box2.Text + "' and Column3='" + box3.Text + "'");
if (dr.Length > 1)
{
ScriptManager.RegisterStartupScript(this, this.GetType(), "CropImage", "alert('you can not insert duplicate record.');", true);
}
else
{
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 = 0; 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++;
}
}
}
}
protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
{
SetInitialRow();
}
}
protected void ButtonAdd_Click(object sender, EventArgs e)
{
AddNewRowToGrid();
}
VB.Net
Private Sub SetInitialRow()
Dim dt As DataTable = New DataTable()
Dim dr As DataRow = Nothing
dt.Columns.Add(New DataColumn("RowNumber", GetType(String)))
dt.Columns.Add(New DataColumn("Column1", GetType(String)))
dt.Columns.Add(New DataColumn("Column2", GetType(String)))
dt.Columns.Add(New DataColumn("Column3", GetType(String)))
dr = dt.NewRow()
dr("RowNumber") = 1
dr("Column1") = String.Empty
dr("Column2") = String.Empty
dr("Column3") = String.Empty
dt.Rows.Add(dr)
ViewState("CurrentTable") = dt
Gridview1.DataSource = dt
Gridview1.DataBind()
End Sub
Private Sub AddNewRowToGrid()
Dim rowIndex As Integer = 0
If ViewState("CurrentTable") IsNot Nothing Then
Dim dtCurrentTable As DataTable = CType(ViewState("CurrentTable"), DataTable)
Dim drCurrentRow As DataRow = Nothing
If dtCurrentTable.Rows.Count > 0 Then
Dim box1 As TextBox = Nothing
Dim box2 As TextBox = Nothing
Dim box3 As TextBox = Nothing
For i As Integer = 1 To dtCurrentTable.Rows.Count
box1 = CType(Gridview1.Rows(rowIndex).Cells(1).FindControl("TextBox1"), TextBox)
box2 = CType(Gridview1.Rows(rowIndex).Cells(2).FindControl("TextBox2"), TextBox)
box3 = CType(Gridview1.Rows(rowIndex).Cells(3).FindControl("TextBox3"), TextBox)
drCurrentRow = dtCurrentTable.NewRow()
drCurrentRow("RowNumber") = i + 1
dtCurrentTable.Rows(i - 1)("Column1") = box1.Text
dtCurrentTable.Rows(i - 1)("Column2") = box2.Text
dtCurrentTable.Rows(i - 1)("Column3") = box3.Text
rowIndex += 1
Next
Dim dr As DataRow() = dtCurrentTable.[Select]("Column1 = '" & box1.Text & "' and Column2='" + box2.Text & "' and Column3='" + box3.Text & "'")
If dr.Length > 1 Then
ScriptManager.RegisterStartupScript(Me, Me.[GetType](), "CropImage", "alert('you can not insert duplicate record.');", True)
Else
dtCurrentTable.Rows.Add(drCurrentRow)
End If
ViewState("CurrentTable") = dtCurrentTable
Gridview1.DataSource = dtCurrentTable
Gridview1.DataBind()
End If
Else
Response.Write("ViewState is null")
End If
SetPreviousData()
End Sub
Private Sub SetPreviousData()
Dim rowIndex As Integer = 0
If ViewState("CurrentTable") IsNot Nothing Then
Dim dt As DataTable = CType(ViewState("CurrentTable"), DataTable)
If dt.Rows.Count > 0 Then
For i As Integer = 0 To dt.Rows.Count - 1
Dim box1 As TextBox = CType(Gridview1.Rows(rowIndex).Cells(1).FindControl("TextBox1"), TextBox)
Dim box2 As TextBox = CType(Gridview1.Rows(rowIndex).Cells(2).FindControl("TextBox2"), TextBox)
Dim box3 As TextBox = CType(Gridview1.Rows(rowIndex).Cells(3).FindControl("TextBox3"), TextBox)
box1.Text = dt.Rows(i)("Column1").ToString()
box2.Text = dt.Rows(i)("Column2").ToString()
box3.Text = dt.Rows(i)("Column3").ToString()
rowIndex += 1
Next
End If
End If
End Sub
Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
If Not Page.IsPostBack Then
SetInitialRow()
End If
End Sub
Protected Sub ButtonAdd_Click(ByVal sender As Object, ByVal e As EventArgs)
AddNewRowToGrid()
End Sub
Screenshot
![](https://imgur.com/NDOrIhm.gif)