How to change DataList Button color which is inside GridView using C# and VB.Net in ASP.Net

Hi Vasanth057,

I have created sample that full-fill your requirement. Refer the below sample.

HTML

<asp:GridView ID="rptrbus" runat="server" AutoGenerateColumns="false" DataKeyNames="ID"
    OnRowDataBound="rptrbus_RowDataBound">
    <Columns>
        <asp:BoundField DataField="Id" HeaderText="Id" />
        <asp:BoundField DataField="Name" HeaderText="Name" />
        <asp:BoundField DataField="Country" HeaderText="Country" />
        <asp:TemplateField HeaderText="Seat">
            <ItemTemplate>
                <asp:DataList runat="server" ID="dlSeat" OnItemDataBound="dlSeat_ItemDataBound">
                    <ItemTemplate>
                        <asp:Label ID="lblSeat" Text='<%# Eval("Seat") %>' runat="server" />
                        <asp:Button ID="btnSave" Text="Save" runat="server" />
                    </ItemTemplate>
                </asp:DataList>
            </ItemTemplate>
        </asp:TemplateField>
    </Columns>
</asp:GridView>

Code

C#

protected void Page_Load(object sender, EventArgs e)
{
    if (!this.IsPostBack)
    {
        DataTable dt = new DataTable();
        dt.Columns.AddRange(new DataColumn[3] { new DataColumn("Id", typeof(int)), new DataColumn("Name"), new DataColumn("Country") });
        dt.Rows.Add(1, "John Hammond", "United States");
        dt.Rows.Add(2, "Mudassar Khan", "India");
        dt.Rows.Add(3, "Suzanne Mathews", "France");
        dt.Rows.Add(4, "Robert Schidner", "Russia");
        rptrbus.DataSource = dt;
        rptrbus.DataBind();
    }
}

protected void rptrbus_RowDataBound(object sender, GridViewRowEventArgs e)
{
    if (e.Row.RowType == DataControlRowType.DataRow)
    {
        string id = rptrbus.DataKeys[e.Row.RowIndex].Value.ToString();
        DataList dlseat = e.Row.FindControl("dlSeat") as DataList;
        DataTable dt = new DataTable();
        dt.Columns.AddRange(new DataColumn[2] { new DataColumn("Id", typeof(int)), new DataColumn("Seat", typeof(int)) });
        dt.Rows.Add(1, 0);
        dt.Rows.Add(2, 1);
        dt.Rows.Add(3, 1);
        dt.Rows.Add(4, 0);
        DataRow[] row = dt.Select("Id=" + id);
        DataTable dt1 = dt.Clone();
        foreach (DataRow dr in row)
        {
            dt1.ImportRow(dr);
        }
        dlseat.DataSource = dt1;
        dlseat.DataBind();
    }
}

protected void dlSeat_ItemDataBound(object sender, DataListItemEventArgs e)
{
    if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
    {
        Label seat = e.Item.FindControl("lblSeat") as Label;
        Button btn = e.Item.FindControl("btnSave") as Button;
        if (seat.Text.Trim() == "1")
        {
            btn.BackColor = System.Drawing.Color.Red;
            btn.ForeColor = System.Drawing.Color.White;
        }
    }
}

VB.Net

Protected Sub Page_Load(sender As Object, e As EventArgs)
	If Not Me.IsPostBack Then
		Dim dt As New DataTable()
		dt.Columns.AddRange(New DataColumn(2) {New DataColumn("Id", GetType(Integer)), New DataColumn("Name"), New DataColumn("Country")})
		dt.Rows.Add(1, "John Hammond", "United States")
		dt.Rows.Add(2, "Mudassar Khan", "India")
		dt.Rows.Add(3, "Suzanne Mathews", "France")
		dt.Rows.Add(4, "Robert Schidner", "Russia")
		rptrbus.DataSource = dt
		rptrbus.DataBind()
	End If
End Sub

Protected Sub rptrbus_RowDataBound(sender As Object, e As GridViewRowEventArgs)
	If e.Row.RowType = DataControlRowType.DataRow Then
		Dim id As String = rptrbus.DataKeys(e.Row.RowIndex).Value.ToString()
		Dim dlseat As DataList = TryCast(e.Row.FindControl("dlSeat"), DataList)
		Dim dt As New DataTable()
		dt.Columns.AddRange(New DataColumn(1) {New DataColumn("Id", GetType(Integer)), New DataColumn("Seat", GetType(Integer))})
		dt.Rows.Add(1, 0)
		dt.Rows.Add(2, 1)
		dt.Rows.Add(3, 1)
		dt.Rows.Add(4, 0)
		Dim row As DataRow() = dt.[Select](Convert.ToString("Id=") & id)
		Dim dt1 As DataTable = dt.Clone()
		For Each dr As DataRow In row
			dt1.ImportRow(dr)
		Next
		dlseat.DataSource = dt1
		dlseat.DataBind()
	End If
End Sub

Protected Sub dlSeat_ItemDataBound(sender As Object, e As DataListItemEventArgs)
	If e.Item.ItemType = ListItemType.Item OrElse e.Item.ItemType = ListItemType.AlternatingItem Then
		Dim seat As Label = TryCast(e.Item.FindControl("lblSeat"), Label)
		Dim btn As Button = TryCast(e.Item.FindControl("btnSave"), Button)
		If seat.Text.Trim() = "1" Then
			btn.BackColor = System.Drawing.Color.Red
			btn.ForeColor = System.Drawing.Color.White
		End If
	End If
End Sub

Screenshot