yup its work thanks a million :
<asp:EntityDataSource ID="EntityDataSource4" runat="server" AutoGenerateWhereClause="True" ConnectionString="name=ARS_DBEntities2" DefaultContainerName="ARS_DBEntities2" EntitySetName="Seats" Select="it.[SeatId], it.[SeatName], it.[SeatStatus]" Where="">
<SelectParameters>
<asp:ControlParameter ControlID="DropDownList1" DbType="Int16" Name="flighId" PropertyName="SelectedValue" />
</SelectParameters>
<WhereParameters>
<asp:ControlParameter ControlID="DropDownList1" DbType="Int16" Name="FlightId" PropertyName="SelectedValue" />
<asp:FormParameter DefaultValue="notbooked" FormField="it.[SeatStatus]" Name="SeatStatus" />
</WhereParameters>
</asp:EntityDataSource>