Pass multiple DropDownList value in QueryString to another page and populate GridView using C# and VB.Net in ASP.Net

Hi ukd,

I have created a sample. Check this example. Now please take its reference and correct your code.

For this sample I have used of NorthWind database that you can download using the link given below.

Download Northwind Database

Namespaces

C#

using System.Configuration;
using System.Data.SqlClient;
using System.Data;

VB.Net

Imports System.Data.SqlClient
Imports System.Data

HTML

First.aspx

<div>
    City:
    <asp:DropDownList runat="server" ID="ddlCities">
    </asp:DropDownList>
    Country:
    <asp:DropDownList runat="server" ID="ddlCountries">
    </asp:DropDownList>
    <br />
    <asp:Button Text="Transfer" OnClick="Transfer" runat="server" />
</div>

Extract.aspx

<asp:GridView runat="server" ID="gvCustomers" AutoGenerateColumns="false">
    <Columns>
        <asp:BoundField DataField="CustomerID" HeaderText="CustomerID" />
        <asp:BoundField DataField="ContactName" HeaderText="ContactName" />
        <asp:BoundField DataField="City" HeaderText="City" />
        <asp:BoundField DataField="Country" HeaderText="Country" />
    </Columns>
</asp:GridView>

C#

First.aspx.cs

protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        PopulateDropDownList(ddlCities, "City", "City", "SELECT DISTINCT City FROM Customers WHERE City <> ''");
        PopulateDropDownList(ddlCountries, "Country", "Country", "SELECT DISTINCT Country FROM Customers WHERE Country <> ''");
    }
}

protected void Transfer(object sender, EventArgs e)
{
    if (ddlCountries.SelectedItem.Text.ToLower() != "select" && ddlCities.SelectedItem.Text.ToLower() != "select")
    {
        Response.Redirect("Extract.aspx?Country=" + ddlCountries.SelectedValue + "&City=" + ddlCities.SelectedValue);
    }
}

private void PopulateDropDownList(DropDownList ddl, string dataTextField, string dataValueField, string query)
{
    string constr = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
    using (SqlConnection con = new SqlConnection(constr))
    {
        using (SqlCommand cmd = new SqlCommand(query, con))
        {
            using (SqlDataAdapter da = new SqlDataAdapter(cmd))
            {
                DataSet ds = new DataSet();
                da.Fill(ds);
                ddl.DataTextField = dataTextField;
                ddl.DataValueField = dataValueField;
                ddl.DataSource = ds;
                ddl.DataBind();
                ddl.Items.Insert(0, new System.Web.UI.WebControls.ListItem("Select", "0"));
            }
        }
    }
}

Extract.aspx.cs

protected void Page_Load(object sender, EventArgs e)
{
    if (!string.IsNullOrEmpty(Request.QueryString["Country"]) && !string.IsNullOrEmpty(Request.QueryString["City"]))
    {
        string country = Request.QueryString["Country"];
        string city = Request.QueryString["City"];
        Response.Write(string.Format("Country is : <b>{0}</b> <br/> City is : <b>{1}</b>", country, city));
        string str = "SELECT CustomerID,ContactName,City,Country FROM Customers WHERE City = '" + city + "' AND Country = '" + country + "'";
        DataTable dt = GetDataTable(str);
        if (dt.Rows.Count > 0)
        {
            gvCustomers.DataSource = dt;
            gvCustomers.DataBind();
        }
        else
        {
            ClientScript.RegisterClientScriptBlock(this.GetType(), "", "alert('No record found as per your criteria!')", true);
        }
    }
}

private DataTable GetDataTable(string query)
{
    DataSet ds = new DataSet();
    string constr = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
    using (SqlConnection con = new SqlConnection(constr))
    {
        using (SqlCommand cmd = new SqlCommand(query, con))
        {
            using (SqlDataAdapter da = new SqlDataAdapter(cmd))
            {
                da.Fill(ds);
            }
        }
    }

    return ds.Tables[0];
}

VB.Net

First.aspx.vb

Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
    If Not IsPostBack Then
        PopulateDropDownList(ddlCities, "City", "City", "SELECT DISTINCT City FROM Customers WHERE City <> ''")
        PopulateDropDownList(ddlCountries, "Country", "Country", "SELECT DISTINCT Country FROM Customers WHERE Country <> ''")
    End If
End Sub

Protected Sub Transfer(ByVal sender As Object, ByVal e As EventArgs)
    If ddlCountries.SelectedItem.Text.ToLower() <> "select" AndAlso ddlCities.SelectedItem.Text.ToLower() <> "select" Then
        Response.Redirect("Extract.aspx?Country=" & ddlCountries.SelectedValue & "&City=" + ddlCities.SelectedValue)
    End If
End Sub

Private Sub PopulateDropDownList(ByVal ddl As DropDownList, ByVal dataTextField As String, ByVal dataValueField As String, ByVal query As String)
    Dim constr As String = ConfigurationManager.ConnectionStrings("constr").ConnectionString
    Using con As SqlConnection = New SqlConnection(constr)
        Using cmd As SqlCommand = New SqlCommand(query, con)
            Using da As SqlDataAdapter = New SqlDataAdapter(cmd)
                Dim ds As DataSet = New DataSet()
                da.Fill(ds)
                ddl.DataTextField = dataTextField
                ddl.DataValueField = dataValueField
                ddl.DataSource = ds
                ddl.DataBind()
                ddl.Items.Insert(0, New System.Web.UI.WebControls.ListItem("Select", "0"))
            End Using
        End Using
    End Using
End Sub

Extract.aspx.vb

Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
    If Not String.IsNullOrEmpty(Request.QueryString("Country")) AndAlso Not String.IsNullOrEmpty(Request.QueryString("City")) Then
        Dim country As String = Request.QueryString("Country")
        Dim city As String = Request.QueryString("City")
        Response.Write(String.Format("Country is : <b>{0}</b> <br/> City is : <b>{1}</b>", country, city))
        Dim str As String = "SELECT CustomerID,ContactName,City,Country FROM Customers WHERE City = '" & city & "' AND Country = '" & country & "'"
        Dim dt As DataTable = GetDataTable(str)
        If dt.Rows.Count > 0 Then
            gvCustomers.DataSource = dt
            gvCustomers.DataBind()
        Else
            ClientScript.RegisterClientScriptBlock(Me.[GetType](), "", "alert('No record found as per your criteria!')", True)
        End If
    End If
End Sub

Private Function GetDataTable(ByVal query As String) As DataTable
    Dim ds As DataSet = New DataSet()
    Dim constr As String = ConfigurationManager.ConnectionStrings("constr").ConnectionString
    Using con As SqlConnection = New SqlConnection(constr)
        Using cmd As SqlCommand = New SqlCommand(query, con)
            Using da As SqlDataAdapter = New SqlDataAdapter(cmd)
                da.Fill(ds)
            End Using
        End Using
    End Using

    Return ds.Tables(0)
End Function

Screenshot