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Editorial Team
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Asked: 2026-05-31T03:32:10+00:00

I’ve created a search function with 3 DropDownLists and a search button. How will

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I’ve created a search function with 3 DropDownLists and a search button. How will I display it on the same page?

Here’s my code:

public partial class Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            //read sql server connection string from web.config file
            string constring = ConfigurationManager.ConnectionStrings["AccreString"].ConnectionString;
            SqlConnection conn = new SqlConnection(constring);
            DataTable dt = new DataTable("emed_province");

            using (conn)
            {
                conn.Open();
                SqlCommand comm = new SqlCommand("SELECT *  FROM emed_province ORDER BY PROVINCE_NAME ASC", conn);
                SqlDataAdapter adptr = new SqlDataAdapter(comm);
                adptr.Fill(dt);
            }

            ddlProvince.DataSource = dt;
            ddlProvince.DataTextField = "PROVINCE_NAME";
            ddlProvince.DataValueField = "PROVINCE_CODE";
            ddlProvince.DataBind();
        }
    }

    protected void ddlProvince_SelectedIndexChanged(object sender, EventArgs e)
    {
        string constring = ConfigurationManager.ConnectionStrings["AccreString"].ConnectionString;
        SqlConnection conn = new SqlConnection(constring);
        DataTable dt = new DataTable("emed_province");

        using (conn)
        {
            conn.Open();
            PROVINCE_CODE = '" + ddlProvince.SelectedValue + "'", conn);
            SqlCommand comm = new SqlCommand("SELECT * FROM emed_city WHERE PROVINCE_CODE =@pcode", conn);
            comm.Parameters.AddWithValue("@pcode", ddlProvince.SelectedValue);
            SqlDataAdapter adptr = new SqlDataAdapter(comm);
            adptr.Fill(dt);

            SqlParameter param = new SqlParameter();
            param.ParameterName = "@pcode";
            param.Value = ddlProvince;

            comm.Parameters.Add(param);
        }
        ddlCity.DataSource = dt;
        ddlCity.DataTextField = "CITY_NAME";
        ddlCity.DataValueField = "CITY_CODE";
        ddlCity.DataBind();
    }

    protected void ddlCity_SelectedIndexChanged(object sender, EventArgs e)
    {
        string constring = ConfigurationManager.ConnectionStrings["AccreString"].ConnectionString;
        SqlConnection conn = new SqlConnection(constring);
        DataTable dt = new DataTable("emed_city");

        using (conn)
        {
            conn.Open();
        PROVINCE_CODE = '" + ddlProvince.SelectedValue + "'", conn);
            SqlCommand comm = new SqlCommand("SELECT * FROM emed_doctors_hospitals     WHERE CITY_CODE =@ccode", conn);
            comm.Parameters.AddWithValue("@ccode", ddlCity.SelectedValue);
            SqlDataAdapter adptr = new SqlDataAdapter(comm);
            adptr.Fill(dt);

            SqlParameter param = new SqlParameter();
            param.ParameterName = "@ccode";
            param.Value = ddlCity;

            comm.Parameters.Add(param);
        }
        ddlSched.DataSource = dt;
        ddlSched.DataTextField = "SCHEDULE";
        ddlSched.DataValueField = "HOSPITAL_CODE";
        ddlSched.DataBind();
    }
    protected void Button1_Click(object sender, EventArgs e)
    {

    }
}

When someone selects a value in the DropDownList and hits the button, it will display the lists of doctors available in the province, city and per particular schedule.

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1 Answer

  1. Editorial Team
    1. Check this sample. I have used SQLDatasource with SelectParameters for this example (you
      can replace it with your own object datasource, custom binding etc.) SQLDataSource Select Parameters
    2. The second dropdownlist automatically populates when the first dropdownlist is changed
    3. On Button even I am just selecting the currently selected values of each dropdownlist (You can select your doctor list in the same way)

    ASPX

        <%@ Page Language="C#" AutoEventWireup="true" CodeFile="Cascading DropDown.aspx.cs"
    Inherits="Cascading_DropDown" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head runat="server">
    <title></title> </head> <body>
    <form id="form1" runat="server">
    <div>
        <label>
            Category:</label>
        <asp:DropDownList ID="ddlCategories" runat="server" AppendDataBoundItems="True" AutoPostBack="True"
            DataSourceID="sdsCategory" DataTextField="CategoryName" DataValueField="CategoryID"
            OnSelectedIndexChanged="ddlCategories_SelectedIndexChanged">
            <asp:ListItem Text="-Select-" Value="" />
        </asp:DropDownList>
        <br />
        <label>
            Products:</label>
        <asp:DropDownList ID="ddlProducts" runat="server" DataSourceID="sdsProducts" DataTextField="ProductName"
            DataValueField="ProductID">
        </asp:DropDownList>
        <asp:Button ID="Button1" runat="server" Text="Search Prodcut" OnClick="Button1_Click" />
        &nbsp;<asp:Label ID="lblSelectedValues" runat="server"></asp:Label>
    </div>
    <asp:SqlDataSource ID="sdsCategory" runat="server" ConnectionString="<%$ ConnectionStrings:NorthwindConnectionString %>"
        SelectCommand="SELECT [CategoryID], [CategoryName] FROM [Categories] ORDER BY [CategoryName]">
    </asp:SqlDataSource>
    <asp:SqlDataSource ID="sdsProducts" runat="server" ConnectionString="<%$ ConnectionStrings:NorthwindConnectionString %>"
        SelectCommand="SELECT [ProductID], [ProductName] FROM [Alphabetical list of products] WHERE ([CategoryID] = @CategoryID)">
        <SelectParameters>
            <asp:ControlParameter ControlID="ddlCategories" Name="CategoryID" PropertyName="SelectedValue"
                Type="Int32" />
        </SelectParameters>
    </asp:SqlDataSource>
    </form> </body> </html>

    .CS

    protected void Page_Load(object sender, EventArgs e)
{

}
protected void ddlCategories_SelectedIndexChanged(object sender, EventArgs e)
{
    if (ddlCategories.SelectedValue == "")
    {
        ddlProducts.Items.Clear();
        ddlProducts.SelectedIndex = -1;
    }

}
protected void Button1_Click(object sender, EventArgs e)
{
    lblSelectedValues.Text = "You selected Category:" + ddlCategories.SelectedItem.Text + " & prodcut:" + ddlProducts.SelectedItem.Text;
}

    You can drop a gridview on form like Abel said & on your button click event, fetch each drop down list selected value & execute your query & databaind your gridview like you are already doing with your drop down lists.

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