Check whether ASP.Net GridView Row is selected or not on Button Click using C# and VB.Net

Hi dorsa,

Please refer below sample.

You can't use required field validator in commandfield , So please use below code for validating-

HTML

<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" DataKeyNames="CustomerId">
    <Columns>
        <asp:BoundField DataField="CustomerId" HeaderText="CustomerId" SortExpression="CustomerId"
            HeaderStyle-CssClass="header-center" />
        <asp:BoundField DataField="Name" HeaderText="Name" SortExpression="Name" HeaderStyle-CssClass="header-center" />
        <asp:BoundField DataField="Country" HeaderText="Country" SortExpression="Country"
            HeaderStyle-CssClass="header-center" />
        <asp:CommandField SelectText="select" ShowSelectButton="True" />
    </Columns>
    <FooterStyle BackColor="White" ForeColor="#000066" HorizontalAlign="Right" VerticalAlign="Middle" />
    <HeaderStyle BackColor="#006699" Font-Bold="True" ForeColor="White" />
    <PagerStyle BackColor="White" ForeColor="#000066" HorizontalAlign="Left" />
    <RowStyle ForeColor="#000066" />
    <SelectedRowStyle BackColor="#669999" Font-Bold="True" ForeColor="White" />
    <SortedAscendingCellStyle BackColor="#F1F1F1" />
    <SortedAscendingHeaderStyle BackColor="#007DBB" />
    <SortedDescendingCellStyle BackColor="#CAC9C9" />
    <SortedDescendingHeaderStyle BackColor="#00547E" />
    <SelectedRowStyle BackColor="LightCyan" ForeColor="DarkBlue" Font-Bold="true" />
</asp:GridView>
<asp:Button Text="Submit" runat="server" OnClick="Check" />

Namespaces

C#

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

VB.Net

Imports System.Data.SqlClient
Imports System.Data

Code

C#

protected void Page_Load(object sender, EventArgs e)
{
    string constr = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
    using (SqlConnection con = new SqlConnection(constr))
    {
        using (SqlCommand cmd = new SqlCommand("SELECT * FROM Customers", con))
        {
            using (SqlDataAdapter da = new SqlDataAdapter(cmd))
            {
                using (DataTable dt = new DataTable())
                {
                    da.Fill(dt);
                    this.GridView1.DataSource = dt;
                    this.GridView1.DataBind();
                }
            }
        }
    }
}
protected void Check(object sender, EventArgs e)
{
    if (GridView1.SelectedValue == null)
    {
        ScriptManager.RegisterStartupScript(this, this.GetType(), "alert", "alert('please selecte row');", true);
    }
}

VB.Net

Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
    Dim constr As String = ConfigurationManager.ConnectionStrings("constr").ConnectionString
    Using con As SqlConnection = New SqlConnection(constr)
        Using cmd As SqlCommand = New SqlCommand("SELECT * FROM Customers", con)
            Using da As SqlDataAdapter = New SqlDataAdapter(cmd)
                Using dt As DataTable = New DataTable()
                    da.Fill(dt)
                    Me.GridView1.DataSource = dt
                    Me.GridView1.DataBind()
                End Using
            End Using
        End Using
    End Using
End Sub

Protected Sub Check(ByVal sender As Object, ByVal e As EventArgs)
    If GridView1.SelectedValue Is Nothing Then
        ScriptManager.RegisterStartupScript(Me, Me.GetType(), "alert", "alert('please selecte row');", True)
    End If
End Sub

Screenshot