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Example doesn't seem to use 'Selected' variable.


I am slightly confused by the Syncfusion example provided here:

Where is the 'Selected' variable being used in a SQL query? It doesn't seem to be used in a query anywhere in the example you have provided?

To me it looks like you are assigning the value of the drop down list to a session variable but that variable is not being used anywhere in a SQL 'WHERE' clause?



1 Reply

PO Prince Oliver Syncfusion Team April 30, 2019 09:05 AM UTC

Hello Alex,  
Thank you for contacting us. 
Based on your requirement in forum 144217 , we have provided sample to store the selected value from DropDownList in a session variable. Now , we have modified the sample by passing this session variable value through SQL query on button click. The second DropDownList in the page will be populated based on this SQL query. Similarly you can pass query with the session variable and repopulate the charts with user’s selection based on your requirement. Please find the modified code and sample below 
<ej:DropDownList runat="server" ID="TradesDropDown" DataTextField="CustomerID" DataValueField="ShipCity" AutoPostBack="true" DataSourceID="SqlData" Width="200px" EnableIncrementalSearch="False" FilterType="Contains" SelectedIndex="0" OnValueSelect="TradesDropDown_ValueSelect"> 
    <asp:SqlDataSource ID="SqlData" runat="server" ConnectionString="<%$ ConnectionStrings:SQLConnectionString %>" SelectCommand="SELECT * FROM [Orders]"> 
            <asp:Parameter Name="ShipCity" Type="String" DefaultValue="Reims" /> 
    <ej:Button runat="server" ID="btn" OnClick="btn_Click" Text="Send Query"></ej:Button> 
    <asp:Label runat="server" Text="Items matching the selected ShipCity value will be bound as dataSource of the below DropDownList when send query button is clicked"></asp:Label> 
    <ej:DropDownList runat="server" ID="DropDownList1" DataTextField="CustomerID" DataValueField="ShipCity"> 
protected void TradesDropDown_ValueSelect(object sender, Syncfusion.JavaScript.Web.DropdownListEventArgs e) 
            Session["ShipCity"] = e.Value; 
        protected void btn_Click(object Sender, Syncfusion.JavaScript.Web.ButtonEventArgs e) 
            string selected  = Session["ShipCity"].ToString(); 
            dt = new DataTable("Order"); 
            cmd.Connection = myConnection; 
            cmd.CommandText = "select [CustomerID] from [Orders] where [ShipCity]='" + selected + "'"; 
            cmd.CommandType = CommandType.Text; 
            SqlDataAdapter da = new SqlDataAdapter(); 
            da.SelectCommand = cmd; 
            if ((myConnection.State == ConnectionState.Closed)) 
            Session["NewDataSource"] = dt; 
            DropDownList1.DataSource = Session["NewDataSource"];  
Let us know if you need any further assistance on this. 

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