how to bind dataset with gridview

This is my code .aspx.cs page ``` public string makequery() { string query = string.Empty; if (ddlPortal2.SelectedValue == "Select" && tbFrom.Text == null && tbTo.Text == null && ddlQuery.SelectedValue == "Select") { query = "SELECT * FROM Form3 and ORDER BY CONVERT(VARCHAR(25), [Datetime], 101) between '" + tbFrom.Text + "' and '" + tbTo.Text + "' DESC"; return query; } else if(ddlPortal2.SelectedItem.Text!="Select" && tbFrom.Text!=null && tbTo.Text!=null && ddlQuery.SelectedItem.Text=="Select") { query = "Select * from Form3 where Portal='" + ddlPortal2.SelectedValue + "' and ORDER BY CONVERT(VARCHAR(25), [Datetime], 101) between '" + tbFrom.Text + "' and '" + tbTo.Text + "' DESC"; return query; } else if (ddlPortal2.SelectedItem.Text != "Select" && tbFrom.Text == null && tbTo.Text == null && ddlQuery.SelectedItem.Text != "Select") { query = "Select * from Form3 where Portal='" + ddlPortal2.SelectedValue + "' and ORDER BY CONVERT(VARCHAR(25), [Datetime], 101) between '" + tbFrom.Text + "' and '" + tbTo.Text + "' DESC"; return query; } return null; } public void GridViewBind() { string query = makequery(); DataSet ds = new DataSet(); if (ds != null) { if (ds.Tables[0].Rows.Count != 0) { GridView1.DataSource = ds; GridView1.DataBind(); } else { GridView1.DataSource = null; GridView1.DataBind(); } } } protected void btnSearch_Click(object sender, EventArgs e) { this.GridViewBind(); } ``` } .aspx page code: ``` <div id="Portal" runat="server"> <asp:Label ID="lblPortal" runat="server" Text="Select Portal"/> <asp:DropDownList ID="ddlPortal2" runat="server" AutoPostBack="True"> <asp:ListItem>Select</asp:ListItem> <asp:ListItem>TRAVELONG</asp:ListItem> <asp:ListItem>ONETRAVEL</asp:ListItem> <asp:ListItem>.UK-BSP</asp:ListItem> <asp:ListItem>.CV-YYZ</asp:ListItem> <asp:ListItem>.CV-YVR</asp:ListItem> </asp:DropDownList> <asp:Label ID="lbFrom" Text="From" runat="server" /> <asp:TextBox ID="tbFrom" runat="server" /> <asp:RequiredFieldValidator ID="rfvFrom" runat="server" ControlToValidate="tbFrom" ErrorMessage="Enter Valid Date">*</asp:RequiredFieldValidator> <asp:Label ID="lblto" Text="To" runat="server" /> <asp:TextBox ID="tbTo" runat="server" /> <asp:RequiredFieldValidator ID="rfvTo" runat="server" ControlToValidate="tbTo" ErrorMessage="Enter To date">*</asp:RequiredFieldValidator> <asp:DropDownList ID="ddlQuery" runat="server" Width="87px"> <asp:ListItem>All</asp:ListItem> <asp:ListItem Value="Query ">Query</asp:ListItem> <asp:ListItem>Non Query</asp:ListItem> </asp:DropDownList> <asp:Button ID="btnSearch" runat="server" Text="Search" onclick="btnSearch_Click" ValidationGroup="1"/><br /> <br /> <asp:ValidationSummary ID="ValidationSummary1" runat="server" /> </div> <div id="Main" runat="server"> <asp:GridView ID="GridView1" runat="server" CellPadding="4" ForeColor="#333333" GridLines="None" onrowcommand="GridView1_RowCommand" AutoGenerateColumns="False"> <Columns> <asp:TemplateField HeaderText="Select"> <itemtemplate> <asp:LinkButton CommandName="cmdBind" runat="server" Text='<%#Eval("ID")%>' ID="ID" ToolTip='<%#Eval("ID")%>'>LinkButton </asp:LinkButton> </itemtemplate> </asp:TemplateField> <asp:TemplateField HeaderText="Date"> <ItemTemplate> <asp:Label ID="lblDateTime" runat="server" Text='<%# Eval("DateTime","{0:d}") %>'></asp:Label> </ItemTemplate> </asp:TemplateField> <asp:BoundField DataField="Portal" HeaderText="Portal" SortExpression="Portal" ItemStyle-HorizontalAlign="Center"/> <asp:BoundField DataField="TID" HeaderText="TID" SortExpression="TID" ItemStyle-HorizontalAlign="Center"/> <asp:BoundField DataField="PNR" HeaderText="PNR" SortExpression="PNR" ItemStyle-HorizontalAlign="Center"/> <asp:BoundField DataField="TicketNumber" HeaderText="TicketNumber" SortExpression="TicketNumber" ItemStyle-HorizontalAlign="Center"/> <asp:TemplateField HeaderText="Unused Tkt Amount" SortExpression="ddlUnusedAmount" ItemStyle-HorizontalAlign="Center"> <ItemTemplate> <asp:Label ID="lblUnusedAmount" runat="server" Text='<%#Eval("UnusedTicketAmount")+ "-" + Eval("ddlUnusedAmount")%>' ></asp:Label> </ItemTemplate> </asp:TemplateField> <asp:TemplateField HeaderText="Penality" SortExpression="ddlAirlinePenality" ItemStyle-HorizontalAlign="Center"> <ItemTemplate> <asp:Label ID="lblAirlinePenality" runat="server" Text='<%#Eval("AirlinePenality")+ "-" + Eval("ddlAirlinePenality")%>' ></asp:Label> </ItemTemplate> </asp:TemplateField> <asp:TemplateField HeaderText="Net Refund" SortExpression="ddlNetRefundProcess" ItemStyle-HorizontalAlign="Center"> <ItemTemplate> <asp:Label ID="lblNetRefund" runat="server" Text='<%#Eval("NetRefundProcess")+ "-" + Eval("ddlNetRefundProcess")%>' ></asp:Label> </ItemTemplate> </asp:TemplateField> <asp:TemplateField HeaderText="Refundable Commission" SortExpression="ddlRefundableCommission" ItemStyle-HorizontalAlign="Center"> <ItemTemplate> <asp:Label ID="lblRefundableCommission" runat="server" Text='<%#Eval("RefundableCommission")+ "-" + Eval("ddlRefundableCommission")%>' ></asp:Label> </ItemTemplate> </asp:TemplateField> <asp:BoundField DataField="ESACCode" HeaderText="ESACCode" SortExpression="ESACCode" ItemStyle-HorizontalAlign="Center"/> <asp:BoundField DataField="WaiverCode" HeaderText="WaiverCode" SortExpression="WaiverCode" ItemStyle-HorizontalAlign="Center"/> <asp:BoundField DataField="RefundType" HeaderText="RefundType" SortExpression="RefundType" ItemStyle-HorizontalAlign="Center" /> <asp:BoundField DataField="Comment" HeaderText="Bart Comment" ItemStyle-HorizontalAlign="Center"/> <asp:BoundField DataField="Query" HeaderText="ARC Verified" ItemStyle-HorizontalAlign="Center" /> </Columns> ``` Now here I make two function one to make query and second to bind that query with `dataset` with `gridview` when I bind `dataset` Cannot find table 0. what I want is when I select field and press search button I can view details in my grid according to the selected fields but I can't bind it with my `dataset`. Can you guys help me with this.