How to open Dropdown on another Dropdown selection in Asp.net

Introduction: In this post I will try to explain how we can open another dropdown on another dropdown selection and insert their data in to database.

Description:

I have created four tables.

BOOK_NAME

BOOK_ID	int
BOOK_NAME	varchar(50)

BOOK_ID is primary key.

PUBLICATION_NAME

PUBLICATION_ID	int
PUBLICATION_NAME	varchar(50)
BOOK_ID_FK	varchar(50)

PUBLICATION_ID is primary key and BOOK_ID_FK is foreign key.

AUTHOR_NAME

AUTHOR_ID	int
AUTHOR_NAME	varchar(50)
PUBLICATION_ID_FK	varchar(50)

AUTHOR_ID is primary key and PUBLICATION_ID_FK is foreign key.

BOOK_DETAIL

Id	int
BOOK	varchar(50)
PUBLICATION	varchar(50)
AUTHOR	varchar(50)

Open visual studio and add new webform to application.

. Add the Connectionstring in web.config file of website.

<configuration>

       <system.web>

              <compilation debug="true" targetFramework="4.0"/>

       </system.web>

       <connectionStrings>

              <add name="CON" connectionString="Data Source=SYS-1F78031ED0A;Initial Catalog=TestBlog;Integrated Security=True"/>

       </connectionStrings>

</configuration>

Drag and drop the Dropdownlist controls from Toolbox.

  <table><tr><td>

        Book Name:&nbsp;</td><td> <asp:DropDownList ID="drpbook" runat="server" AutoPostBack="True"

            onselectedindexchanged="DropDownList1_SelectedIndexChanged">

        </asp:DropDownList></td></tr>  

       <tr><td>&nbsp;&nbsp;&nbsp;&nbsp;</td></tr>

      <tr> <td> Publication Name:</td><td><asp:DropDownList ID="drppublication" runat="server" AutoPostBack="True"

            onselectedindexchanged="DropDownList2_SelectedIndexChanged">

        </asp:DropDownList></td></tr>

        <tr><td>&nbsp;&nbsp;&nbsp;&nbsp;</td></tr>

        <tr><td>  Author Name :  </td>

        <td> <asp:DropDownList ID="dropauthor" runat="server">

        </asp:DropDownList></td></tr>

        <tr><td>&nbsp;&nbsp;&nbsp;&nbsp;</td></tr>

       <tr><td></td><td> <asp:Button ID="btnsave" runat="server" Text="Insert" onclick="btnsave_Click" /></td></tr>

         </table>

Now go to .aspx.cs page.

using System.Data;

using System.Data.SqlClient;

using System.Configuration;

SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["CON"].ToString());

    protected void Page_Load(object sender, EventArgs e)

    {

        if(!IsPostBack)

        {

            Binddropdown();

        }

    }

    protected void DropDownList2_SelectedIndexChanged(object sender, EventArgs e)

    {

        string query = "select * from AUTHOR_NAME where PUBLICATION_ID_FK=" + drppublication.SelectedValue + "";

        SqlCommand cmd = new SqlCommand(query, con);

        SqlDataAdapter adp = new SqlDataAdapter(cmd);

        DataTable dt = new DataTable();

        adp.Fill(dt);

        dropauthor.DataSource = dt;

        dropauthor.DataTextField = "AUTHOR_NAME";

        dropauthor.DataValueField = "AUTHOR_ID";

        dropauthor.DataBind();

        dropauthor.Items.Insert(0, new ListItem("---Select---", "0"));

    }

    private void Binddropdown()

    {

        SqlDataAdapter adp = new SqlDataAdapter("Select * from BOOK_NAME", con);

        DataTable dt = new DataTable();

        adp.Fill(dt);

        drpbook.DataSource = dt;

        drpbook.DataTextField = "BOOK_NAME";

        drpbook.DataValueField = "BOOK_ID";

        drpbook.DataBind();

        drpbook.Items.Insert(0, new ListItem("---Select---", "0"));

        drppublication.Items.Insert(0, new ListItem("---Select---", "0"));

        dropauthor.Items.Insert(0, new ListItem("---Select---", "0"));

    }

    protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)

    {

        string query = "select * from PUBLICATION_NAME where BOOK_ID_FK='" + drpbook.SelectedValue + "'";

        SqlCommand cmd = new SqlCommand(query, con);

        SqlDataAdapter adp = new SqlDataAdapter(cmd);

        DataTable dt = new DataTable();

        adp.Fill(dt);

        drppublication.DataSource = dt;

        drppublication.DataTextField = "PUBLICATION_NAME";

        drppublication.DataValueField = "PUBLICATION_ID";

        drppublication.DataBind();

        drppublication.Items.Insert(0, new ListItem("---Select---", "0"));

    }

    protected void btnsave_Click(object sender, EventArgs e)

    {

        string command = "insert into BOOK_DETAIL(BOOK,PUBLICATION,AUTHOR) values('"+drpbook.SelectedItem+"','"+drppublication.SelectedItem+"','"+dropauthor.SelectedItem+"')";

        SqlCommand cmd = new SqlCommand(command, con);

        con.Open();

            cmd.ExecuteNonQuery();

        dropauthor.SelectedIndex =-1;

        drppublication.SelectedIndex = -1;

        drpbook.SelectedIndex = -1;

        Response.Write("Data Save Successfully");

    }

In VB

Imports System.Data

Imports System.Data.SqlClient

Imports System.Configuration

Private con As New SqlConnection(ConfigurationManager.ConnectionStrings("CON").ToString())

    Protected Sub DropDownList1_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles drpbook.SelectedIndexChanged

        Dim query As String = "select * from PUBLICATION_NAME where BOOK_ID_FK='" + drpbook.SelectedValue & "'"

        Dim cmd As New SqlCommand(query, con)

        Dim adp As New SqlDataAdapter(cmd)

        Dim dt As New DataTable()

        adp.Fill(dt)

        drppublication.DataSource = dt

        drppublication.DataTextField = "PUBLICATION_NAME"

        drppublication.DataValueField = "PUBLICATION_ID"

        drppublication.DataBind()

        drppublication.Items.Insert(0, New ListItem("---Select---", "0"))

    End Sub

    Private Sub Binddropdown()

        Dim adp As New SqlDataAdapter("Select * from BOOK_NAME", con)

        Dim dt As New DataTable()

        adp.Fill(dt)

        drpbook.DataSource = dt

        drpbook.DataTextField = "BOOK_NAME"

        drpbook.DataValueField = "BOOK_ID"

        drpbook.DataBind()

        drpbook.Items.Insert(0, New ListItem("---Select---", "0"))

        drppublication.Items.Insert(0, New ListItem("---Select---", "0"))

        dropauthor.Items.Insert(0, New ListItem("---Select---", "0"))

    End Sub

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

        If Not IsPostBack Then

            Binddropdown()

        End If

    End Sub

    Protected Sub DropDownList2_SelectedIndexChanged(ByVal sender As Object, ByVal e As EventArgs)

        Dim query As String = "select * from AUTHOR_NAME where PUBLICATION_ID_FK=" + drppublication.SelectedValue & ""

        Dim cmd As New SqlCommand(query, con)

        Dim adp As New SqlDataAdapter(cmd)

        Dim dt As New DataTable()

        adp.Fill(dt)

        dropauthor.DataSource = dt

        dropauthor.DataTextField = "AUTHOR_NAME"

        dropauthor.DataValueField = "AUTHOR_ID"

        dropauthor.DataBind()

        dropauthor.Items.Insert(0, New ListItem("---Select---", "0"))

    End Sub

    Protected Sub btnsave_Click(ByVal sender As Object, ByVal e As EventArgs)

        Dim command As String = "insert into BOOK_DETAIL(BOOK,PUBLICATION,AUTHOR) values ('" & drpbook.SelectedItem.Text & "','" & drppublication.SelectedItem.Text & "','" & dropauthor.SelectedItem.Text & "')"

        Dim cmd As New SqlCommand(command, con)

        con.Open()

        cmd.ExecuteNonQuery()

        dropauthor.SelectedIndex = -1

        drppublication.SelectedIndex = -1

        drpbook.SelectedIndex = -1

        Response.Write("Data Save Successfully")

    End Sub

Now run the project and check the result.

Related Articles on Dropdownlist:

Ø  How to bindDropdownlist with XML file in Asp.net?

Ø  How to bind Dropdownlist with database in Asp.net?

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