Add RowDatabound event :
protected void gv_Details1_RowDataBound(object sender, GridViewRowEventArgs e)
{
if (e.Row.RowType == DataControlRowType.DataRow)
{
e.Row.Attributes.Add("style", "cursor:pointer;");
string abc = ((GridView)sender).DataKeys[e.Row.RowIndex].Value.ToString();
e.Row.Attributes["onClick"] = "location.href='pagename.aspx?Rumid=" + abc + "'";
}
}
Thanks :