load a row from a database table after dropdown choice

Hi,
my name is Sara and i'm a new user here. I use Chronoforms v4 for a short time and I have a problem..
(sorry for my english but I don't speak it very well..I hope to explain the problem in the best way)
I create a data entry form and relative table to save data here I post the code:

<div class="ccms_form_element cfdiv_header" id="autoID-f65eac7559464f1273560644cb0b8ebe_container_div"><h1>Anagrafica Allevatore</h1><div class="clear"></div></div><div class="ccms_form_element cfdiv_text" id="autoID-d8beb1c9c0c94e465bb0b56115e90eda_container_div"><label>RNA</label><input maxlength="150" size="30" class="" title="" type="text" value="" name="rna" />
<div class="small-message">Inserire l'RNA in maiuscolo</div><div class="clear"></div><div id="error-message-rna"></div></div><div class="ccms_form_element cfdiv_text" id="autoID-52d4e7a4b3a4d1d394b482b08796fcdf_container_div"><label>Cognome</label><input maxlength="150" size="30" class="" title="" type="text" value="" name="cognome" />
<div class="clear"></div><div id="error-message-cognome"></div></div><div class="ccms_form_element cfdiv_text" id="autoID-6b52f6ac40cd006e831c8df7c7a84033_container_div"><label>Nome</label><input maxlength="150" size="30" class="" title="" type="text" value="" name="nome" />
<div class="clear"></div><div id="error-message-nome"></div></div><div class="ccms_form_element cfdiv_text" id="autoID-ca81cb57d6a2f0b532ecdedc5f359eb4_container_div"><label>Telefono</label><input maxlength="150" size="30" class=" validate['number']" title="" type="text" value="" name="tel" />
<div class="clear"></div><div id="error-message-tel"></div></div><div class="ccms_form_element cfdiv_text" id="autoID-e68ec4513bc2587bd79ce8487cc04b0b_container_div"><label>Indirizzo</label><input maxlength="150" size="30" class="" title="" type="text" value="" name="indirizzo" />
<div class="clear"></div><div id="error-message-indirizzo"></div></div><div class="ccms_form_element cfdiv_text" id="autoID-de6891a973aa33ac4fbd39da991aa5ff_container_div"><label>CAP</label><input maxlength="150" size="30" class=" validate['number']" title="" type="text" value="" name="cap" />
<div class="clear"></div><div id="error-message-cap"></div></div><div class="ccms_form_element cfdiv_text" id="autoID-3025030b63e1c25a619dfa11b643d361_container_div"><label>Città</label><input maxlength="150" size="30" class="" title="" type="text" value="" name="citta" />
<div class="clear"></div><div id="error-message-citta"></div></div><div class="ccms_form_element cfdiv_text" id="autoID-bb9cb3f3375e6172e78a639a5e3c3fdd_container_div"><label>Associazione</label><input maxlength="150" size="30" class="" title="" type="text" value="" name="associazione" />
<div class="clear"></div><div id="error-message-associazione"></div></div><div class="ccms_form_element cfdiv_submit" id="autoID-6e9f4310e7a2098fb12c12a371f934d5_container_div"><input name="conferma" class="" value="Conferma" type="submit" />
 <input type='reset' name='reset' value='Reset' /><div class="clear"></div><div id="error-message-conferma"></div></div>

After this I can select data by code called RNA with a dropdown; for this I create a form that contains only a dropdown and a submit button (with reset button connected) the code is as follows:

<h1>Scegliere il codice RNA dall'elenco</h1><?php
 
$nome_selected = JRequest::getInt('rna', '', 'post');
$db =& JFactory::getDBO();
 
$query = "
 
SELECT `cf_id`,`rna`, `cognome`,`nome`,`tel`,`indirizzo`,`cap`,`citta`,`associazione`
 FROM `#__chronoforms_data_anagrafica_clienti2`
 ORDER BY `cf_id`
";
$db->setQuery($query);
$nomes = $db->loadAssocList();
$nome_options = "";
foreach ( $nomes as $v ) {
 if ( $nome_selected == $v['rna'] ) {
 $selected = "selected='selected'";
 } else {
 $selected = '';
 }
 
 $nome_options .= "<option value='".$v['cf_id']."' $selected >".$v['rna']."</option>";
 
}
?>


<div>
 <div>
 <label style="width: 250px;">RNA</label>
 <select id="select_1" size="1" title=""  name="scelta_rna">
 <!--<option value="">Choose Option</option>
 <option value="option 1">option 1</option>
 <option value="option 2">option 2</option>
 <option value="option 3">option 3</option> -->
 
 <?php echo $nome_options; ?>
 
 </select>
 
 </div>
 <div> </div>
</div><div class="ccms_form_element" id="input_cont_av">
<a href="index.php?option=com_chronoforms&chronoform=anag_per_iscrizioni&scelta=".$posted['select_rna']"">
<input name="input_avanti" class="" value="Avanti" type="button" />
</a>
<div class="clear"></div></div>

I have not connected the DB to the dropdown using "Action" but with the code inserted at the beginning of the form; to load the data I use another form as the previous one, but how do I connect the form with the dropdown to the next to allow loading data?

This is only a part of a "problem" because I have to create a kind of "management" because I have a table "anagrafica_clienti" and another one "prodotti" and I have to create a third that allows me to combine customer and product

Hi Sara,

Sorry for the delay I was away when you posted this message.

The easiest way to pass data between forms is to use the 'Data to Session' and 'Session to Data' actions.

Bob