Trying to save selected item on listbox in a single column in database

Question

i am trying to save selected item on listbox in a single column in database as comma separated.

<td>                
                <%--<asp:DropDownList ID="ddlCertific" runat="server" class='form-control'></asp:DropDownList>--%>
                <asp:ListBox ID="ddlCertific" runat="server"  SelectionMode="Multiple">                                    
                </asp:ListBox>
            </td>

binding data on page load

void BindDropdown()
    {
        dt = conn.GetData("SELECT CODE_DESC as datac from code ");
        ddlCertific.DataSource = dt;
        ddlCertific.DataTextField = "datac";
        ddlCertific.DataValueField = "datac";

        ddlCertific.DataBind();
    }

Datasaving in database

protected void submit(object sender, EventArgs e)
    {
      string CERTIFIC;
CERTIFIC = ddlCertific.Text;
conn.IUD("INSERT INTO BAM(CERTIFIC) values ('"+ CERTIFIC +"')");
     }

Any idea would be appreciated.

Answer 1

Here are the steps after some research and it is working for me

1. Added listbox as per question

   <asp:ListBox ID="ddlCertific" runat="server"  SelectionMode="Multiple" Width="229px">
               <asp:ListItem Value="test1">test1</asp:ListItem>
               <asp:ListItem Value="test2">test2</asp:ListItem>
               <asp:ListItem Value="test3">test3</asp:ListItem>
               <asp:ListItem Value="test4">test4</asp:ListItem>
    </asp:ListBox>
   

2. Added a hidden field - Tricky part

   <asp:HiddenField runat="server" ID="HiddenField1" ClientIDMode="Static" OnValueChanged="Date_ValueChanged" />
   

3. Javascript - This will add the selected items in the listbox using a ',' and do a post back since we need value at server

   <script type="text/javascript">
   function getSelectedOptions(sel) {
       var opts = [], opt;
       var a = [];
   
       // loop through options in select list
       for (var i=0, len=sel.options.length; i<len; i++) {
           opt = sel.options[i];
   
           // check if selected
           if ( opt.selected ) {
               // add to array of option elements to return from this function
               opts.push(opt);
               a.push(opt.value + ', '); 
          }
       }
   
       document.getElementById('HiddenField1').value = a.toString();
       // return array containing references to selected option elements
       return opts;
     }
   
    document.getElementById('ddlCertific').onchange = function (e)
   
   {
         getSelectedOptions(this);
   
         abc();
          //__doPostBack
     };
   
     function abc() {
   
         document.getElementById('HiddenField1').value;
           __doPostBack('HiddenField1'); 
     }
   
    </script> 
   

4. Add client postback reference on server side and hiddenfield change event.

   protected void Page_Load(object sender, EventArgs e)
   {
   
       string val = ClientScript.GetPostBackEventReference(this,"");
    }
   
     protected void Date_ValueChanged(object sender, EventArgs e)
   {
       string value = HiddenField1.Value;
       //do your db stuffs
   }