In this article i will show you, How to bind Dropdownlist with the Country, State and City table using SqlDataSource. We all that If among tables are related to each other then we can show among tables one by one on indexChanged event. So, First of all design tables following ways:
[CountryTable]
CountryId int primary_key Identity(1,1)
Country_Name nvarchar(100)
[State]
StateId int primary_key Identity(1,1)
State_Name nvarchar(100)
CountryId int
[City]
CityId int primary_key Identity(1,1)
City_Name nvarchar(100)
StateId int
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="countrystatecity.aspx.cs" Inherits="countrystatecity" %>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>
Select Country :
<asp:DropDownList ID="DropDownList1" runat="server" AppendDataBoundItems="True" AutoPostBack="True" DataSourceID="SqlDataSource1" DataTextField="CountryName" DataValueField="CountryId" Height="19px" OnSelectedIndexChanged="DropDownList1_SelectedIndexChanged" Width="150px">
<asp:ListItem Value="0">Select</asp:ListItem>
</asp:DropDownList>
<asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:ConnectionString %>" SelectCommand="SELECT * FROM [Country]"></asp:SqlDataSource>
<br />
<br />
Select State :
<asp:DropDownList ID="DropDownList2" runat="server" AppendDataBoundItems="True" AutoPostBack="True" DataSourceID="SqlDataSource2" DataTextField="StateName" DataValueField="StateId" Height="19px" OnSelectedIndexChanged="DropDownList2_SelectedIndexChanged" Width="150px">
<asp:ListItem Value="0">Select</asp:ListItem>
</asp:DropDownList>
<asp:SqlDataSource ID="SqlDataSource2" runat="server" ConnectionString="<%$ ConnectionStrings:ConnectionString %>" SelectCommand="SELECT * FROM [State] WHERE ([CountryId] = @CountryId)">
<SelectParameters>
<asp:ControlParameter ControlID="DropDownList1" Name="CountryId" PropertyName="SelectedValue" Type="Int32" />
</SelectParameters>
</asp:SqlDataSource>
<br />
<br />
Select City : <asp:DropDownList ID="DropDownList3" runat="server" AppendDataBoundItems="True" DataSourceID="SqlDataSource3" DataTextField="CityName" DataValueField="CityId" Height="19px" Width="150px">
<asp:ListItem Value="0">Select</asp:ListItem>
</asp:DropDownList>
<asp:SqlDataSource ID="SqlDataSource3" runat="server" ConnectionString="<%$ ConnectionStrings:ConnectionString %>" SelectCommand="SELECT * FROM [City] WHERE ([StateId] = @StateId)">
<SelectParameters>
<asp:ControlParameter ControlID="DropDownList2" Name="StateId" PropertyName="SelectedValue" Type="Int32" />
</SelectParameters>
</asp:SqlDataSource>
</div>
</form>
</body>
</html>
[CountryTable]
CountryId int primary_key Identity(1,1)
Country_Name nvarchar(100)
[State]
StateId int primary_key Identity(1,1)
State_Name nvarchar(100)
CountryId int
[City]
CityId int primary_key Identity(1,1)
City_Name nvarchar(100)
StateId int
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="countrystatecity.aspx.cs" Inherits="countrystatecity" %>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>
Select Country :
<asp:DropDownList ID="DropDownList1" runat="server" AppendDataBoundItems="True" AutoPostBack="True" DataSourceID="SqlDataSource1" DataTextField="CountryName" DataValueField="CountryId" Height="19px" OnSelectedIndexChanged="DropDownList1_SelectedIndexChanged" Width="150px">
<asp:ListItem Value="0">Select</asp:ListItem>
</asp:DropDownList>
<asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:ConnectionString %>" SelectCommand="SELECT * FROM [Country]"></asp:SqlDataSource>
<br />
<br />
Select State :
<asp:DropDownList ID="DropDownList2" runat="server" AppendDataBoundItems="True" AutoPostBack="True" DataSourceID="SqlDataSource2" DataTextField="StateName" DataValueField="StateId" Height="19px" OnSelectedIndexChanged="DropDownList2_SelectedIndexChanged" Width="150px">
<asp:ListItem Value="0">Select</asp:ListItem>
</asp:DropDownList>
<asp:SqlDataSource ID="SqlDataSource2" runat="server" ConnectionString="<%$ ConnectionStrings:ConnectionString %>" SelectCommand="SELECT * FROM [State] WHERE ([CountryId] = @CountryId)">
<SelectParameters>
<asp:ControlParameter ControlID="DropDownList1" Name="CountryId" PropertyName="SelectedValue" Type="Int32" />
</SelectParameters>
</asp:SqlDataSource>
<br />
<br />
Select City : <asp:DropDownList ID="DropDownList3" runat="server" AppendDataBoundItems="True" DataSourceID="SqlDataSource3" DataTextField="CityName" DataValueField="CityId" Height="19px" Width="150px">
<asp:ListItem Value="0">Select</asp:ListItem>
</asp:DropDownList>
<asp:SqlDataSource ID="SqlDataSource3" runat="server" ConnectionString="<%$ ConnectionStrings:ConnectionString %>" SelectCommand="SELECT * FROM [City] WHERE ([StateId] = @StateId)">
<SelectParameters>
<asp:ControlParameter ControlID="DropDownList2" Name="StateId" PropertyName="SelectedValue" Type="Int32" />
</SelectParameters>
</asp:SqlDataSource>
</div>
</form>
</body>
</html>